Bony Core Research Articles

Genetic Foundation of Male Spur Length and Its Correlation with Female Egg Production in Chickens.

Spurs, which mainly appear in roosters, are protrusions near the tarsometatarsus on both sides of the calves of chickens, and are connected to the tarsometatarsus by a bony core. As a male-biased morphological characteristic, the diameter and length of spurs vary significantly between different individuals, mainly related to genetics and age. As a specific behavior of hens, egg-laying also varies greatly between individuals in terms of traits such as age at first egg (AFE), egg weight (EW), and so on. At present, there are few studies on chicken spurs. In this study, we investigated the inheritance pattern of the spur trait in roosters with different phenotypes and the correlations between spur length, body weight at 18 weeks of age (BW18), shank length at 18 weeks of age (SL18), and the egg-laying trait in hens (both hens and roosters were from the same population and were grouped according to their family). These traits related to egg production included AFE, body weight at first egg (BWA), and first egg weight (FEW). We estimated genetic parameters based on pedigree and phenotype data, and used variance analysis to calculate broad-sense heritability for correcting the parameter estimation results. The results showed that the heritability of male left and right spurs ranged from 0.6 to 0.7. There were significant positive correlations between left and right spur length, BW18, SL18, and BWA, as well as between left and right spur length and AFE. We selected 35 males with the longest spurs and 35 males with the shortest spurs in the population, and pooled them into two sets to obtain the pooled genome sequencing data. After genome-wide association and genome divergency analysis by FST, allele frequency differences (AFDs), and XPEHH methods, we identified 7 overlapping genes (CENPE, FAT1, FAM149A, MANBA, NFKB1, SORBS2, UBE2D3) and 14 peak genes (SAMD12, TSPAN5, ENSGALG00000050071, ENSGALG00000053133, ENSGALG00000050348, CNTN5, TRPC6, ENSGALG00000047655,TMSB4X, LIX1, CKB, NEBL, PRTFDC1, MLLT10) related to left and right spur length through genome-wide selection signature analysis and a genome-wide association approach. Our results identified candidate genes associated with chicken spurs, which helps to understand the genetic mechanism of this trait and carry out subsequent research around it.

Polycerate sheep in Nigeria

A prospective cross-sectional study was carried out on indigenous flocks of sheep around Maiduguri Metropolis and Jere of Borno State, North-East Nigeria from September, 2016 to March, 2017 to evaluate the frequency and odds of occurrence of Polycerate sheep in Northern Nigeria. Gross examination of a total of 25, 989 sheep of different breeds, age, weight and of either sex was implored. A frequency of occurrence was rated at 0.023 with an odd of occurrence of 1:4330.5 was observed. A total of 4 Polycerate sheep were Ouda breeds and 2 Polycerates were Yankasa breeds while scurs were found mostly on the Balami breed. Findings from the study shows the existence of indigenous viable and productive breeds of sheep with 3, 4, 5 and more horns in the region. Craniographs shows multiple horns originates from the same horn base on the skull on each side and there is evidence of a hard bony core. Campaigns to create awareness on the importance to science and rites, preservation, protection and genetic sequencing of indigenous polycerates as it compares to other polycerates of the world should be organized in the region.

Lead uptake into calcified and keratinized compartments of horns from a convenience sample of lead-dosed goats

ABSTRACT Hair and/or nail analyses are sometimes used in biomonitoring studies due to the convenience of sample collection, storage, and transport, as well as the potential to assess past exposures to toxic metals, such as lead (Pb). However, the validity of Pb measurements in these keratinized matrices as biomarkers of absorbed dose remains unclear. The aim of this study was to examine the uptake of Pb into horns harvested postmortem from 11 goats that received a cumulative oral dose of up to 151 g Pb acetate over a period of 1–11 years as part of a long-term blood Pb proficiency testing program. Uptake of Pb into keratinized horn was compared to the corresponding underlying bony horn core, which, as part of the bone compartment, provided a measure of absorbed Pb dose. Two complementary analytical techniques were used to assess Pb: X-Ray Fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Detectable amounts of Pb were found in all keratinized horn samples (0.45–6.6 µg/g) and in all but one bony core sample (1.4–68 µg/g). In both bony core and keratinized horn samples, Pb accumulation increased with dose over a low-to-moderate cumulative-dose interval, consistent with previous observations, but plateaued at higher doses. Significant associations were observed between Pb in keratinized horn and bony core samples particularly with XRF measurements, which represent the surface bone compartment. These findings provide evidence that Pb is excreted in keratinized tissues but reflects only a small fraction of the absorbed Pb dose, likely transferred from underlying bone tissue.

A Curious Case of Cutaneous Horn

Cutaneous horns are uncommon lesions that occur as conical projections in various sun-exposed parts of the body. They are made of hyperkeratotic material and look similar to animal horns. These lesions lack a central bony core that differentiates them from the animal horns. They are frequently associated with various benign, premalignant, and malignant lesions, and therefore carry a clinical significance. We present a case of a 58-year-old gentleman who presented with a conical projection over the center of the forehead, which was clinically diagnosed as a cutaneous horn. Excision of the horn along with the base was done, and the histopathology revealed benign seborrheic keratosis as the underlying lesion. The excision of small lesions along with their bases or biopsy of the base of large lesions is of paramount importance in the management of cutaneous horns.

Understanding the effects of the bovine POLLED variants.

Horns are paired appendages on the head of bovine species, comprising an inner bony core and outer keratin sheath. The horn bud forms during early fetal development but ossification of the developing horn does not occur until approximately 1month after birth. Little is known about the genetic pathways that lead to horn growth. Hornless, or polled, animals are found in all domestic bovids. Histological studies of bovine fetuses have shown that the horn bud does not form in polled individuals. There are currently four known genetic variants for polledness in cattle on BTA1. All of the variants are intergenic, but probably affect regulation of nearby genes or long non-coding RNAs. Transcriptomic studies suggest that the expression of two nearby long non-coding RNAs are affected by the Celtic POLLED variant, but further studies are required to confirm these data. Candidate genes located elsewhere in the genome are involved in regulating bone formation and epithelial-to-mesenchymal transition. Expression of one of these candidate genes, RXFP2, appears to be reduced in the fetal horn bud of polled animals carrying the Celtic variant compared with horned individuals. Investigating horn ontogenesis and the genetic pathway by which the POLLED variants prevent horn development has implications for cattle breeding. If the genetic basis of horn bud formation and polledness is better understood, then new targets may be identified for precision genome editing to create polled individuals.

Anatomical features of the tongue of two chiropterans endemic in the Egyptian fauna; the Egyptian fruit bat (Rousettus aegyptiacus) and insectivorous bat (Pipistrellus kuhlii)

The current study aimed to investigate the tongue (lingual) morphometry, histology, and histochemistry of two chiropterans endemic in the Egyptian fauna, and having different feeding preferences. The tongues of nine adult individuals of each species were utilized in our investigation. The tongue of fruit-eating bat was observed relatively longer than the one of insect-eating bat. Grossly, the insect-eating bat had a lingual prominence on the dorsum of lingual body, while the fruit-eating bat had a concave midline over the lingual body. Histologically, numerous forms of lingual papillae were scattered along the dorsal epithelium of the tongue. The lingual papillae of the fruit-eating bat seem to be well adapted for piercing the skin of a fruit and liquid sap retention. The lingual glands of both species were lodged in the muscular layer. Two main sets were identified; the serous von Ebner's gland usually seen accompanied by the circumvallate papillae and Weber's gland with mixed mucoserous secretions. Von Ebner's gland showed more prominent acidic mucins, while Weber's gland expressed neutral mucins. The lingual epithelium of the fruit-eating bat had an outer covering of cornified non-nucleated epithelium. On the other hand, the insect-eating bat had an outer covering of nucleated epithelium. It is for the first time to record the existence of the entoglossal plates of both species which consisted of a bony core in the fruit-eating bat and a cartilaginous element in the insect-eating bat. The current study represents an attempt to shed more light on the tongue evolution among mammalian vertebrates.

Quantifying shape and ecology in avian pedal claws: The relationship between the bony core and keratinous sheath.

Terrestrial tetrapods use their claws to interact with their environments in a plethora of ways. Birds in particular have developed a diversity of claw shapes since they are often not bound to terrestrial locomotion and have heterogeneous body masses ranging several orders of magnitude. Numerous previous studies have hypothesized a connection between pedal claw shape and ecological mode in birds, yet have generated conflicting results, spanning from clear ecological groupings based on claw shape to a complete overlap of ecological modes. The majority of these studies have relied on traditional morphometric arc measurements of keratinous sheaths and have variably accounted for likely confounding factors such as body mass and phylogenetic relatedness. To better address the hypothesized relationship between ecology and claw shape in birds, we collected 580 radiographs allowing visualization of the bony core and keratinous sheath shape in 21 avian orders. Geometric morphometrics was used to quantify bony core and keratinous sheath shape and was compared to results using traditional arc measurements. Neither approach significantly separates bird claws into coarse ecological categories after integrating body size and phylogenetic relatedness; however, some separation between ecological groups is evident and we find a gradual shift from the claw shape of ground‐dwelling birds to those of predatory birds. Further, the bony claw core and keratinous sheath are significantly correlated, and the degree of functional integration does not differ across ecological groups. Therefore, it is likely possible to compare fossil bony cores with extant keratinous sheaths after applying corrections. Finally, traditional metrics and geometric morphometric shape are significantly, yet loosely correlated. Based on these results, future workers are encouraged to use geometric morphometric approaches to study claw geometry and account for confounding factors such as body size, phylogeny, and individual variation prior to predicting ecology in fossil taxa.

An exceptionally preserved armored dinosaur reveals the morphology and allometry of osteoderms and their horny epidermal coverings.

Although the evolution and function of “exaggerated” bony projections in ornithischian dinosaurs has been subject to significant debate recently, our understanding of the structure and morphology of their epidermal keratinized coverings is greatly limited. The holotype of Borealopelta, a new nodosaurid ankylosaur, preserves osteoderms and extensive epidermal structures (dark organic residues), in anatomic position across the entire precaudal length. Contrasting previous specimens, organic epiosteodermal scales, often in the form of horn-like (keratinous) sheaths, cap and exaggerate nearly all osteoderms, allowing for morphometric and allometric analyses of both the bony osteoderms and their horny sheaths. A total of 172 osteoderms were quantified, with osteoderm spine length and height being positively allometric with respect to basal length and width. Despite tight correlations between the different measures amongst all other osteoderms, the large parascapular spines represent consistent outliers. Thickness and relative contribution of the keratinized epiosteodermal scales/sheaths varies greatly by region, ranging from 2% to 6% for posterior thoracics, to ∼25% (1.3×) for the parascapular spines—similar to horn sheaths in some bovid analogues. Relative to the bony cores, the horny portions of the spines are strongly positively allometric (slope = 2.3, CI = 1.8–2.8). Strong allometric scaling, species-specific morphology, and significant keratinous extension of the cervicoscapular spines is consistent with elaboration under socio-sexual selection. This marks the first allometric analysis of ornithischian soft tissues.

The bony horncore of the common eland (Taurotragus oryx): composition and mechanical properties of a spiral fighting structure.

Horns are permanent structures projecting from the head of bovids, consisting of a bony horncore covered with a layer of skin and then a sheath of keratinous material showing variability of growth intensity based on nutrition. From the point of view of the horn's mechanical properties, the keratin sheath has been widely studied, but only a few studies have considered the complete structure of the horn and fewer studies have focused on the bony horncore and its characteristics. The latter showed the important role of the bony core, when cranial appendages are subject to mechanical stress (as happens during fighting). The mechanical properties of bone material, along with its mineral profile, are also important, because they can show effects of different factors, such as nutrition and mineral deficiencies in diet. For this reason, eight horncores of captive common eland male were sampled at four positions along the vertical axis of the horn. The main aim was to study variation in mechanical properties and the mineral content along the vertical axis of the horncores. We further analysed whether the spiral bony ridge present on eland horncores differs in any of the studied properties from adjacent parts of the horncore. In other antelopes, spiral ridges on the horns have been proposed to increase grip during wrestling between males. Cross-sections of the horncores were performed at four positions along the longitudinal axis and, for each position, two bone bars were extracted to be tested in impact and bending. Moreover, in the first sampling position (the closest position to the base) two bars were extracted from the spiralled bony area. The resulting fragments were used to measure ash content, bone density and mineral content. Results showed that horn bone decreased along the vertical axis, in ash (-36%), density (-32%), and in impact work 'U' (marginally significant but large effect: -48%). The concentration of several minerals decreased significantly (Mg, Cr, Mn and Tl by -33%, -25%, -31%, -43%, respectively) between the basal and the uppermost sampling site. The bone tissue of the horncore spiral compared with non-spiral bone of the same position showed a lower ash content (53% vs. 57%), Mg and Mn; in addition to showing approximately half values in work to peak force 'W', bending strength 'BS' and 'U', but not in Young's modulus of elasticity 'E'. In conclusion, similarly to the results in a totally different fighting bony structure, the antlers, the horncore of eland shows advantageous parameters in bone tissue of the base in respect to the tip, with higher values for mechanical properties, density and mineral profile. Moreover, the spiral bone tissue showed lower material mechanical properties. Probably the spiral tissue of the horn may have a role in deflecting potential cross-sectional fractures during wrestling. In addition, it may serve to improve the grip during wrestling, and we propose that it may also prevent risk of rotation of sheath with respect to internal bone not only in this, but also in other straight bovid horns.

Building and tanning in the 18th and 19th centuries: an analysis of cattle horncores from Greenwich High Road (London)

SUMMARY: The assemblage from Greenwich High Road has interesting implications for our understanding of 18th- and early 19th-century tanneries and also of the use of bones as building material. The study of the age at death of the animals revealed that the horncores are mostly from fully adult individuals, probably culled draught animals. This hypothesis is supported by biometrical analysis. The comparison of the Greenwich horncores with modern data and archaeological evidence suggests that the Greenwich assemblage is predominantly composed of oxen. The horncores were used to line a drain on the site and are likely to represent waste material resulting from the activities that took place in the nearby tannery. Skins and horns were removed for craft purposes, while the bony cores, with no economic value, were simply used as cheap and ready material to help the construction of the drain.

A Comparative Study of Some Morphological and Microscopic Identifying Features of Genuine Rhino (Rhinoceros unicornis) Horns and Fake Horns

Rhino horn is hard, elongated, conical structure composed entirely of keratin but lacking bony core. Illegal trade of rhino horn has high financial rewards. Both genuine and fake horns are confiscated by authorities and sent for identification. Various morphological and microscopic features of 214 genuine horns of one horned Rhino (Rhinoceros unicornis) stored at Armed Forest Protection Training Centre, Tikauli and Office of the Chitwan National Park, Kasara, Nepal were studied. The studied morphological parameters were color, surface texture, height, mass, basal circumference, frontal groove, basal elevation, porosity, light penetration capability at the base and density. Similarly, microscopic features like shape, size and frequency of filamentous units, Interfilamentous space, ratio of medulla and filamentous unit and laminae were studied after thin transverse sections made from the tip of 140 genuine horns. Some of these features were compared with that of 65 fake horns which were received in the laboratory and identified as fake samples. The distinctive filamentous units were observed in all studied genuine rhino horns with varied number, shape and sizes. Based on this study, identifying features of genuine rhino horns were properly established. The study also reveals the possibility of approximation of maturity of rhino horns.

Structure and function of the cassowary's casque and its implications for cassowary history, biology and evolution

Cassowaries (Casuarius) possess a cranial casque, sheathed by keratin and composed of modified cranial bones. We combine data and hypotheses on three areas of cassowary research. First, we present novel observations on casque anatomy. The bony core is fragile, incorporating a mass of trabeculae anteriorly and an empty space posteriorly. Secondly, we use these observations to evaluate hypotheses of casque function. Implications that the casque evolved within the context of activities involving percussive actions are unlikely and observations that might support these hypotheses are absent. It is most likely that the casque serves a sociosexual role and functions in visual and acoustic display. The similarity in casque form between males and females, combined with male parental investment, makes it plausible that the extravagant structures present in cassowaries evolved within the context of mutual sexual selection. Thirdly, we combine morphological, molecular and geological evidence to provide a new phylogenetic history for cassowaries. We suggest that cassowaries invaded New Guinea in at least two waves and provisionally regard crown–cassowaries as a geologically young, post-Pliocene clade. We provide these hypotheses as areas requiring discussion and urge other workers to test our ideas with new data on cassowary anatomy, behaviour and genetics.

A Model of Sheath of Bovine Horn Coupled Nano-Mechanical Properties and Microstructures

With the long-term evolution, the bovine horn as the primary protective and offensive weapon has superior mechanical properties. The bovine horn consists of two parts, the keratinous horn sheath and the bony core. The keratinous is natural composite material with a highly toughness and can bear impact and repeated loads during fighting. It has a complex hierarchical microarchitecture. To establish the qualitative model for finding the possible relationship between structure and mechanical properties of bovine horn, in this paper, the model was established that based on the parameters provided by microstructure imaging and nanoindentation testing from transverse and longitudinal directions. Which would provide information useful for the developing bionic composite materials for micro-aircraft, bionic tribology, bionic medical apparatus and bionic organs (tissue engineering).

Multi-layered bird beaks: a finite-element approach towards the role of keratin in stress dissipation.

Bird beaks are layered structures, which contain a bony core and an outer keratin layer. The elastic moduli of this bone and keratin were obtained in a previous study. However, the mechanical role and interaction of both materials in stress dissipation during seed crushing remain unknown. In this paper, a multi-layered finite-element (FE) model of the Java finch's upper beak (Padda oryzivora) is established. Validation measurements are conducted using in vivo bite forces and by comparing the displacements with those obtained by digital speckle pattern interferometry. Next, the Young modulus of bone and keratin in this FE model was optimized in order to obtain the smallest peak von Mises stress in the upper beak. To do so, we created a surrogate model, which also allows us to study the impact of changing material properties of both tissues on the peak stresses. The theoretically best values for both moduli in the Java finch are retrieved and correspond well with previous experimentally obtained values, suggesting that material properties are tuned to the mechanical demands imposed during seed crushing.

Tree climbing – a fundamental avian adaptation

There have been a number of studies on the claws of Mesozoic birds, largely driven by interest in the habitat of Archaeopteryx. Many Mesozoic avians have large, well formed manual claws, largely absent in contemporary birds. Juvenile hoatzins are the only living birds with claws that are large enough to be generally functional, but not equivalent to those of Mesozoic birds. When birds developed an effective backstroke permitting easy ascent from flat surfaces, the need for manual claws disappeared, which would suggest that they were primarily used for climbing tree trunks and had little function in prey capture. This hypothesis has both phylogenetic and functional implications. The numerous claw studies to date are based primarily on measurements taken of the bony core, all that is usually preserved in fossils. Examination of contemporary birds shows that this is a poor estimator of the size and shape of the horny sheath that actually forms the functional claw. The discovery of vast numbers of exceptionally preserved fossil birds from the Late Jurassic and Early Cretaceous of China means that we now have an opportunity to compare actual horny claw data from the earliest birds with that of modern birds and test hypotheses on climbing, terrestrial activity, and predation.

Experimental study on the mechanical properties of the horn sheaths from cattle

Bovine horn is composed of a sheath of keratin overlying a bony core. Previous studies of the bovine horn sheath have focused mainly on its morphology and compositions. In the present paper, we performed a series of uniaxial tension, three-point bending, and fracture tests to investigate the structural and mechanical properties of the horn sheaths from subadult cattle, Bos taurus. The effects of hydration on the mechanical properties were examined and their variations along the longitudinal direction of the horn sheath were addressed. Scanning electron microscopy of the fracture surfaces showed that the horn sheath has a layered structure and, more interestingly, the laminae have a rippled appearance. The Young's modulus and tensile strength increase from 850 MPa and 40 MPa at 19% water content to 2.3 GPa and 154 MPa at 0% water content, respectively. The Poisson's ratio of the horn sheath was about 0.38. The critical stress intensity factor was about 4.76 MPa m1/2 at an intermediate hydration (8% water content), greater than that at 0% water content (3.86 MPa m1/2) and 19% water content (2.56 MPa m1/2). The bending properties of the samples varied along the length of the horn. The mean flexural moduli of the specimens in the distal, middle and proximal parts were about 6.26 GPa, 5.93 GPa and 4.98 GPa, respectively; whereas the mean yield strength in the distal segment was about 152.4 MPa, distinctly higher than that in the middle (135.7 MPa) and proximal parts (116.4 MPa). This study deepens our understanding of the relationships among optimal structure, property and function of cattle horn sheaths.

Giant cutaneous horn in an African woman: a case report

IntroductionA cutaneous horn is a conical projection of hyperkeratotic epidermis. Though grossly resembling an animal horn, it lacks a bony core. These lesions have been well described in Caucasian patients, as well as in a number of Arabic and Asian patients.Case presentationA young female presented with a large 'horn' of five-year duration, arising from a burn scar. Excision and scalp reconstruction were performed. Histology was reported as verrucoid epidermal hyperplasia with cutaneous horn.ConclusionThis may be the first documentation of this lesion in a black African. Although likely rare, it should be considered in the differential diagnosis of dermatologic lesions. Up to 40% of cutaneous horns occur as part of a premalignant or malignant lesion, and surgical extirpation with histological examination is thus more important than the curiosity surrounding these lesions.

The ultrastructure of the peri-articular osteophytes - an evaluation by scanning electron microscopy

Osteophytes are intra-articular osteochondral tissues, which are usually found at the margins of degenerating synovial joints. The aetiology or pathogenesis of this tissue has been a subject of protracted debate. The aim of this study was to offer a possible aetiology and or pathogenesis of this expendable yet important osteochondral tissue using the scanning electron microscopy to evaluate the structure of the cartilage mantle of osteophytes and the relationship of this mantle with that of the adjoining normal articular cartilage. Sections of periarticular osteophytes and osteophyte-normal articular cartilage composite tissues were obtained during total knee replacement for osteoarthritis (OA). These sections were routinely processed and examined using the scanning electron microscope with emphasis on the osteophytic cartilage mantle and the merger of the osteophyte and the adjoining normal articular cartilage. The cartilage mantle of osteophytes was found to be thinner but continuous with that of the adjoining normal articular cartilage. However, a longitudinal bar of acellular tissue was found to separate the subchondral bones of both tissues. The cellular (chondrocyte) arrangement in the osteophytic cartilage was similar to that of the adjoining normal articular cartilage. In addition, in the superficial layer, there was looping of collagen fibres between the normal articular cartilage mantle and that of the osteophytic tissues. The continuity between the cartilage mantle of osteophytes and the adjoining normal articular cartilage may suggest that in the formation of osteophytes, the chondrocytes from the adjoining normal articular cartilage greatly influence the mesenchymal tissue precursor of osteophyte to differentiate along a chondrocytic pathway initially. With subsequent vascular invasion probably from the periosteum, the neocartilage develops a bony core with a completely separate blood supply from that of the adjoining subchondral bone.

Invited commentary

Expense, limited availability, and biological variability complicate the use of cadaver specimens for testing mechanical methods of sternal closure. The use of artificial polyurethane models has been common in the development and testing of orthopedic appliances. A simple polyurethane sternal model that stimulates cancellous or medullary bone has been developed for the testing of sternal closure techniques. More complex composite models, which mimic cortical bone applied to a medullary bony core, can be created, but they are more expensive and may provide little advantage.The tests conducted in this study demonstrate a high level of consistency between the simple medullary sternal model and cadaver specimens. This study is very important in that it validates a simple and inexpensive method of testing a wide array of appliances, as well as other techniques of sternal closure. The validation of these models makes it cost effective to test sternal closure methods under a wide variety of conditions using the various destructive methods common in materials testing. Development of better methods of sternal closure will reduce the extreme disability and expense associated with sternal dehiscence. Expense, limited availability, and biological variability complicate the use of cadaver specimens for testing mechanical methods of sternal closure. The use of artificial polyurethane models has been common in the development and testing of orthopedic appliances. A simple polyurethane sternal model that stimulates cancellous or medullary bone has been developed for the testing of sternal closure techniques. More complex composite models, which mimic cortical bone applied to a medullary bony core, can be created, but they are more expensive and may provide little advantage. The tests conducted in this study demonstrate a high level of consistency between the simple medullary sternal model and cadaver specimens. This study is very important in that it validates a simple and inexpensive method of testing a wide array of appliances, as well as other techniques of sternal closure. The validation of these models makes it cost effective to test sternal closure methods under a wide variety of conditions using the various destructive methods common in materials testing. Development of better methods of sternal closure will reduce the extreme disability and expense associated with sternal dehiscence.

The braincase, mandible and dental structures of the Early Devonian lungfish Dipnorhynchus kurikae from Wee Jasper, New South Wales

Dipnorhynchus kurikae Campbell & Barwick was described from the Receptaculites Limestone Member at Wee Jasper. Our new specimens include material of the braincase, the snout, the nasal capsules, the palate and the mandible which were not previously available. The new specimens give new data on the pores in the snout, the arrangement of the soft tissues in the nasal capsule, the growth of the hard tissues on the surface of the dentary, the formation of the hard surface on the palate and the prearticulars, the arrangement of sacculus and the nerves VII, IX and X in the otic region, and the interpretation of the palatoquadrate. The lateral lines on the mandible have been exposed by excavation. Thin sections show that the bone on the overgrowth of the dentary is of the same kind as occurs in the cores of the ridges on the tuberosities and marginal ridges on the palate and prearticular. A thin layer of dentine-like columns which contain no dentine tubules overlie the bony cores. This, and the mode of growth, demonstrate that the dental plates—being made of a bony core—have different patterns of deposition from tooth plates in most later Palaeozoic genera, which are made of dentine. This throws light on the way tooth plates evolved from a dipnorhynchid pattern through a speonesydrionid pattern to true tooth plates. The complex tooth plates of Diabolepis are considered to be independently developed. Ventrally the parasphenoid of Dipnorhynchus kurikae does not divide the pterygoids, but stops short at the posterior end of the pterygoids. The semicircular canals and the superior sinus of the saccular cavity are described from the well-preserved material. In comparison with D. sussmilchi, this species has a number of distinctive features, and is easily recognised as a separate species.