Cuticular Remains Research Articles

Chemical processing of fossil phyllocarid cuticle: a comparison of micro- and macrofossil remains

Cuticular remains of the phyllocarid crustaceans Caryocaris? and Ceratiocaris? obtained via maceration of macrofossil remains in hydrofluoric acid are compared with dispersed fragments isolated using both the low-manipulation HF extraction and the standard HCl–HF–HCl method. The studied specimens were obtained from Ordovician and Silurian shales of the Šárka and Požáry formations (Prague Basin, Barrandian area, Czech Republic). This methodological approach allows a direct comparison of macrofossil remains with microfossils in residue. The differences in residues obtained through the two bulk-rock extraction methods are also discussed.

Preservation and Taphonomy of Fossil Insects from the Earliest Eocene of Denmark.

Simple SummaryInsect fossils dating 55 million-years-old from the Stolleklint Clay and Fur Formation of Denmark are known to preserve both fine morphological details and color patterns. To enhance our understanding on how such fragile animals are retained in the fossil record, we examined a pair of beetle elytra, a wasp and a damselfly using sensitive analytical techniques. In our paper, we demonstrate that all three insect fossils are composed of cuticular remains (that is, traces of the exoskeleton) that, in turn, are dominated by the natural pigment eumelanin. In addition, the beetle elytra show evidence of a delicate lamellar structure comparable to multilayered reflectors that produce metallic hues in modern insects. Our results contribute to improved knowledge on the process of fossilization of insect body fossils in marine environments.Marine sediments of the lowermost Eocene Stolleklint Clay and Fur Formation of north-western Denmark have yielded abundant well-preserved insects. However, despite a long history of research, in-depth information pertaining to preservational modes and taphonomic pathways of these exceptional animal fossils remains scarce. In this paper, we use a combination of scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to assess the ultrastructural and molecular composition of three insect fossils: a wasp (Hymenoptera), a damselfly (Odonata) and a pair of beetle elytra (Coleoptera). Our analyses show that all specimens are preserved as organic remnants that originate from the exoskeleton, with the elytra displaying a greater level of morphological fidelity than the other fossils. TEM analysis of the elytra revealed minute features, including a multilayered epicuticle comparable to those nanostructures that generate metallic colors in modern insects. Additionally, ToF-SIMS analyses provided spectral evidence for chemical residues of the pigment eumelanin as part of the cuticular remains. To the best of our knowledge, this is the first occasion where both structural colors and chemical traces of an endogenous pigment have been documented in a single fossil specimen. Overall, our results provide novel insights into the nature of insect body fossils and additionally shed light on exceptionally preserved terrestrial insect faunas found in marine paleoenvironments.

The role of microbial mats in the exquisite preservation of Aptian insect fossils from the Crato Lagerstätte, Brazil

The insect fossils recorded in the lithographic limestones of the Crato Formation (Aptian of the Araripe Basin, Brazil) have a high degree of morphological fidelity of external and internal anatomical features, including cuticular remains, muscles and organs. The main factor for this exquisite preservation is considered to be the influence of microbial mats in the fossilization process. Petrographic and scanning electron microscope analysis with coupled x-ray spectroscopy (SEM/EDS) showed direct and indirect microbial features associated with the microfabric of the orthopteran insect fossils. We propose a four-steps model for insect fossil preservation, with the capture, protection, creation of the microbial sarcophagus, and mineralization of the organic remains mediated by microbial mats. The confluence of morphological and taphonomic data indicates possible climatic variations on the Aptian of the Araripe Basin, with the exquisitely preserved insect fossils associated with favorable environmental conditions for the installation of microbial mats on the lacustrine substrate.

Diverse cuticular remains in Cambrian (Series 2) SSF assemblages from China and the pioneer metazoan colonization of offshore environments

Our understanding of the early Cambrian bioradiation is largely driven by the contrasting information obtained from small skeletal fossils (SSF) and various types of exceptionally preserved fossils from different parts of the world. In this study, a new ‘Orsten’-type fossil Lagerstätte is reported from the Cambrian Series 2 upper Shuijingtuo Formation in the eastern Three Gorges area, South China. The Shuijingtuo Formation yielded a range of microscopic fragments of metazoan cuticles as well as fragments of possible epithelial tissue. Seventeen different types of micro-ornamentation patterns are recognized on the surface of these cuticular fragments. Based on comparisons with fossil organisms recorded from coeval strata elsewhere, as well as extant relatives, possible affinities with arthropods, palaeoscolecids, acrotretid brachiopods and mollusks are discussed. This ‘Orsten’-type fossil assemblage was deposited in offshore environments, and the lack of evidence for long-distance transportation indicates that a highly diverse fauna was present in, or very close to, the relatively deep shelf settings in the Three Gorges area during the early Cambrian (Epoch 2, Age 3). The invasion of metazoans into deeper, offshore environments could have closely followed, or even been coeval, with their radiation in relatively shallow water settings. Thus, albeit highly fragmented, such cuticular fossils can aid in providing a more complete picture of the Cambrian bioradiation.

Yantaromyiidae, a new family of Diptera (Brachycera: Schizophora) from Tertiary Baltic amber and X-ray synchrotron microtomography imaging of its structures

A new monotypic family, †Yantaromyiidae (Insecta, Diptera, Schizophora), is described from Baltic amber. Yantaromyia arcana gen. et sp. nov. is represented by a single well-preserved male. X-ray synchrotron microtomography is used to reveal details of its morphology. The new family is a schizophoran fly, placed here close to Heleomyzidae + Trixoscelididae + Rhinotoridae, and is erected on the basis of the following combination of (supposed) apomorphies with respect to Schizophora: lunule enlarged and bare, male eyes dichoptic, male abdominal segments 6–8 fused and secondarily almost symmetrical, legs strongly setose, tibiae with two preapical setae dorsally, subscutellum strongly convex, thoracic suture perpendicular to the longitudinal body axis and reaching row of dorsocentrals. Additional characters include: inclinate frontal setae absent, postocellars convergent, frontal vitta setulose, postsutural intraalar absent, anepisternum without strong setae, anepimeron bare, both proepisternal and proepimeral setae present. Microtomography revealed that some cuticular remains are present, displaced and, if occasionally occurring close to the body surface, visible as false pits.http://zoobank.org/urn:lsid:zoobank.org:pub:6C6EF7FF-74CF-4775-A433-B2E850015B74

Caught in the act: priapulid burrowers in early Cambrian substrates.

The fossilized traces of burrowing worms have taken on a considerable importance in studies of the Cambrian explosion, partly because of their use in defining the base of the Cambrian. Foremost among these are the treptichnids, a group of relatively large open probing burrows that have sometimes been assigned to the activities of priapulid scalidophoran worms. Nevertheless, most Cambrian burrows have an uncertain progenitor. Here we report a suite of exceptionally preserved trace and body fossils from sandstones of the lower Cambrian (Stage 4) File Haidar Formation of southern Sweden that can unequivocally be assigned to a scalidophoran producer. We further present the first burrow casts produced via actualistic experiments on living priapulids, and demonstrate the remarkable morphological parallels between these modern and Cambrian fossil equivalents. In addition, co-occurrence of scalidophoran-derived cuticular remains permits a unique synthesis of evidence from trace fossil, body and organic remains. Comparative analysis of these exceptionally preserved fossils supports a scalidophoran producer for treptichnids and by extension suggests a latest Ediacaran origin of the ecdysozoan clade.

Oldest record of the scale-leaved clade of Podocarpaceae, early Paleocene of Patagonia, Argentina

Andruchow-Colombo, A., Escapa, I. H., Carpenter, R. J., Hill, R. S., Iglesias, A., Abarzua, A. M. & Wilf, P. 15 November 2018. Oldest record of the scale-leaved clade of Podocarpaceae, early Paleocene of Patagonia, Argentina. Alcheringa 43, 127–145. ISSN 0311-5518.A new podocarpaceous conifer is described from the early Danian Salamanca Formation (southern Chubut, Patagonia, Argentina) based on compressions of leafy branches with cuticular remains. Kirketapel salamanquensis gen. et sp. nov. has amphistomatic, scale-like leaves with marginal frills distinguishable at the apex; stomata oriented randomly in relation to the major axis of the leaf with four to five subsidiary cells and extremely reduced Florin rings; and irregularly shaped epidermal cells. We compare K. salamanquensis with extant and extinct members of the imbricate-leaved podocarps, among which it closely resembles Florin’s Dacrydium group C genera (i.e., Lagarostrobos, Manoao, Lepidothamnus and Halocarpus). Among these genera, only Lepidothamnus has a living representative in South America, the Chilean L. fonkii, whose leaf macro- and micromorphological characters are described in detail for comparison. Overall, the Patagonian fossil species is most similar to the extant and extinct members of Lagarostrobos in its cuticular micromorphology; however, macromorphological characters, such as the leaf size, apex curvature and mode of flattening, clearly differentiate it from all four genera of Dacrydium group C. We include Kirketapel salamanquensis in a combined molecular and morphological phylogenetic analysis conducted under the maximum parsimony criterion. The new, early Paleocene fossil taxon is confidently recovered as part of the scale-leaved clade as defined herein, which also includes Halocarpus, Phyllocladus, Lepidothamnus, Parasitaxus, Lagarostrobos and Manoao, and it constitutes the oldest record known for the group by at least 17 million years as well as its first fossil occurrence outside Australasia, establishing a widespread Gondwanan history. Furthermore, based on its oldest locality of occurrence, K. salamanquensis shows that the divergence of the total group of the scale-leaved podocarps occurred by at least 65 million years ago, adding to the growing systematic knowledge of earliest Cenozoic macrofloras in the Southern Hemisphere.Ana Andruchow-Colombo [aandruchow@mef.org.ar] and Ignacio Escapa [iescapa@mef.org.ar] CONICET, Museo Paleontológico Egidio Feruglio Av. Fontana 140, Trelew 9100, Chubut, Argentina; Raymond J. Carpenter* [raymond.carpenter@adelaide.edu.au] School of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tas. 7001, Australia; Robert S. Hill [bob.hill@adelaide.edu.au] School of Biological Sciences and Environment Institute, University of Adelaide, Adelaide, SA 5005, Australia; Ari Iglesias [ari_iglesias@yahoo.com.ar] CONICET, Instituto de Investigaciones en Biodiversidad y Medioambiente INIBIOMA-CONICET, Universidad Nacional del COMAHUE, Quintral 1250, San Carlos de Bariloche 8400, Río Negro, Argentina; Ana Abarzua [anaabarzua@uach.cl] Instituto de Ciencias de la Tierra, Facultad de Ciencias, Universidad Austral de Chile, Av. Rector Eduardo Morales Miranda 23, Valdivia 5090000, Región de los Ríos, Chile; Peter Wilf [pwilf@psu.edu] Department of Geosciences, Pennsylvania State University, University Park, PA 16802, USA. *Also affiliated with: School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia.

The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa.

BackgroundEurypterids are a diverse group of chelicerates known from ~250 species with a sparse Ordovician record currently comprising 11 species; the oldest fully documented example is from the Sandbian of Avalonia. The Middle Ordovician (Darriwilian) fauna of the Winneshiek Lagerstätte includes a new eurypterid species represented by more than 150 specimens, including some juveniles, preserved as carbonaceous cuticular remains. This taxon represents the oldest described eurypterid, extending the documented range of the group back some 9 million years.ResultsThe new eurypterid species is described as Pentecopterus decorahensis gen. et sp. nov.. Phylogenetic analysis places Pentecopterus at the base of the Megalograptidae, united with the two genera previously assigned to this family by the shared possession of two or more pairs of spines per podomere on prosomal appendage IV, a reduction of all spines except the pair on the penultimate podomere of appendage V, and an ornamentation of guttalate scales, including angular scales along the posterior margin of the dorsal tergites and in longitudinal rows along the tergites. The morphology of Pentecopterus reveals that the Megalograptidae are representatives of the derived carcinosomatoid clade and not basal eurypterids as previously interpreted.ConclusionsThe relatively derived position of megalograptids within the eurypterids indicates that most eurypterid clades were present by the Middle Ordovician. Eurypterids either underwent an explosive radiation soon after their origination, or earlier representatives, perhaps Cambrian in age, remain to be discovered. The available instars of Pentecopterus decorahensis suggest that eurypterids underwent extreme appendage differentiation during development, a potentially unique condition among chelicerates. The high degree of appendage specialization in eurypterids is only matched by arachnids within chelicerates, supporting a sister taxon relationship between them.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0443-9) contains supplementary material, which is available to authorized users.

NothofagussubgenusBrassospora(Nothofagaceae) leaf fossils from New Zealand: a link to Australia and New Guinea?

Nothofagus palustris sp. nov. is the first record of well-preserved leaves of Nothofagus subgenus Brassospora in New Zealand, and is described from an Oligo–Miocene leaf bed in the Gore Lignite Measures of the South Island. Nothofagus palustris is represented by relatively small and variably toothed leaves with cuticular remains that possess all the characteristic features of the subgenus, including the presence of variably sized stomata that are randomly arranged within areoles, hydathodes along the major veins and ‘bulging cells’ within the areoles on the adaxial side. Phylogenetic assessment shows that the leaves are similar to those of Australian Oligocene and Miocene species and may belong to the same clade of Brassospora. Most notably, these species share the derived feature of abundant leaf wax, a feature that is now only well developed in two New Guinean species. This and other evidence allows the possibility that the ancestor of N. palustris reached New Zealand from Australia. However, it is improbable that N. palustris or a similar species was the common ancestor of the clade of Brassospora that is now confined to New Caledonia. Ecologically, N. palustris is unusual among extant and previously described macrofossil species of Brassospora in being found in a relatively open, swampy habitat. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 174, 503–515.

Plant and animal cuticle remains from the Lower Devonian of southern Poland and their palaeoenvironmental significance

Filipiak, P. & Zaton, M. 2010: Plant and animal cuticle remains from the Lower Devonian of southern Poland and their palaeoenvironmental significance. Lethaia, Vol. 44, pp. 397–409. Assemblages of plant and arthropod remains are reported from the Lower Devonian clastic deposits of the Upper Silesian and Malopolska blocks in southern Poland. Most of the plant and animal remains are palynologically dated as Pragian–Emsian/Eifelian. The plant material comprises higher plant cuticles with stomata classified as Drephanophycus and Sawdonia, and more enigmatic remains (nematophytes) classified as Nematothallus, Cosmochlaina and tubular banded tubes. They are associated with abundant and diverse miospores. Animal remains consist of eurypterid respiratory organs, the morphology of which may presumably point to their advance physiological properties, and cuticular remains of eurypterid and probably scorpion origin, as well as some remains of unknown affinity. The presence of such mixed assemblages in the Lower Devonian of Poland indicate marginal-marine and/or alluvial environments spreading in the southern margin of the Old Red Continent. The dominance of land-derived plant remains and simultaneous scarcity of marine acritarchs indicate that the environment was very weakly influenced by marine conditions. If nematophytes were really related to extant liverworts, as suggested by some workers, they, together with the other associated spore-producing plants, may strongly indicate moist environmental conditions, which may have offered suitable habitats for temporary eurypterid migrations onto land. □Cuticles, eurypterids, Lower Devonian, nematophytes, Poland, spores.

Traces of a limnic food web in the Eocene Lake Messel — a preliminary report based on fish coprolite analyses

The extraordinary fossil preservation of a wide variety of organisms (i.e. algae, arthropods, vertebrates) in the Eocene Lake Messel locality partly allows the reconstruction of an autochthonous food web. Investigations on over 150 fish coprolites from different stratigraphic horizons reveal for the first time cuticular remains of different arthropod taxa including Branchiopod Crustacea (Cladocera, Conchostraca) and Nematocere Diptera (Culicidae, Chaoboridae). The picture of the “hostile” Lake Messel must be revised with these new finds, as there is now evidence for diverse and abundant autochthonous life in the upper water layers. The organisms identified here were part of a complex food web, and thus close the gap between primary producers and fish in the Lake Messel ecosystem. By coprolite analysis, the food web reconstruction presented here is based on evidence of actually eaten oragnisms. Primary producers were pelagic, floating or benthic algae, the latter growing on a substrate (Messel Waterlily and other higher plants). A number of Arthropoda described here (e.g. Culicidae) fed on these algae as primary consumers. Second level consumers include Chaoboridae (described here for Messel for the first time) and Heteroptera. Juvenile and small fish, which in turn were captured by adult predatory fish, crocodiles, turtles, and piscivore mammals represent higher order trophic levels.

Compounds released by sequential chemolysis from cuticular remains of the Cretaceous Gymnosperm Squamastrobus tigrensis (Patagonia, the Argentine)

The chemical composition of morphologically well-preserved cuticular remains of the Cretaceous Gymnosperm Squamastrobus tigrensis found in the Bajo Tigre locality (Patagonia) was analysed by a progressive chemical degradation sequence involving: (i) lipid extraction after ultrasonic treatments; (ii) further BF 3-MeOH transesterification; and (iii) repeated mild NaBO 2-H 2O 2 degradation of the final residue. The compound assemblages released after the successive treatments were considered to reflect lipid speciation patterns in the different levels of the cuticular structure. In particular, after all the treatments, the dominance of a homologous series of α, ω-alkanedioic acids with maxima at C 9 and C 10 indicates a polymethylene network based on macromolecules; the units of this network contain in-chain unsaturations or substitutions in positions similar to those in precursor unsaturated C 16 and C 18 acids. The low yields of ω-hydroxyacids typical of cutins and suberins of extant plants are interpreted as an intense microbial alteration and/or diagenetic transformation of the fossil cuticle. In conjunction with data from infrared spectroscopy and analytical pyrolysis, this suggests that the Squamastrobus remains consist of a macromolecular alkyl mixture in which the original C backbone has been defunctionalized, reoxidized, and subjected to additional condensation by the probable contribution of newly-formed, non-hydrolyzable bridges. It appears that this cellulose-lacking material includes a small moiety of altered lignin, and has been subjected to extensive oxidation, but not to further thermal alteration leading to decarboxylation. A possible result of this diagenetic alteration is that a portion of the resin constituents were transformed into lower molecular weight alkylbenzenes and alkylnaphthalenes, whereas another portion condensed into a very stable, non-hydrolyzable residue. The chemical stability of this residue is not due to aromatization, but to secondary condensation of altered aliphatic biomacromolecules.

Three‐dimensional preservation of arthropod integument from the Middle Cambrian of Australia

Three-dimensional preservation of arthropod soft integument occurs in Middle Cambrian sediments of the Georgina Basin, western Queensland, Australia. The beds are referred to the Monastery Creek Phosphorite Formation, Gowers Formation, Inca Shale Formation and Devon-court Limestone Formation. The finds include arthropod type-A larvae previously described by Muller & Walossek and several complete appendages, possibly of early Palaeozoic ‘ostracodes’, as well as indeterminable cuticular remains. The Australian sediments were in part deposited under high water-energy conditions, whereas previously known occurrences of three-dimensional soft-integument preservation have been from environments of lower water energy. Such preservation may thus be more widespread in the Early Paleozoic than hitherto known. □Phosphatization, arthropods, type-A larvae, appendages, Middle Cambrian, Geogina Basin, Australia, three-dimensional preservation.

A pliocene flora from the subachoque valley (Cordillera Oriental, Colombia)

A palynological and macrobotanical study was made of a 40 cm long peaty clay layer (SUBA 39 section) intercalated in fluvial deposits of Pliocene age from the Subachoque Valley, located at the northwestern border of the high plain of Bogotá in the Cordillera Oriental of Colombia at an elevation of 2820 m above sea level. This has permitted a detailed reconstruction of the former regional and local vegetation cover. The regional one consisted of an admixture of lower tropical, subandean and Andean forest elements that most probably developed in a tropical lowland environment. Few local vegetation elements have been found; only ferns were abundant along the shores of the former closed river branch. This reconstruction represents one of the vegetation types that existed at the beginning of the final upheaval of the northern Andes. All macrofossil types (cuticular remains, fruits, seeds, etc.) and some newly recognized microfossil types (pollen, fungal spores, etc.) found in the SUBA 39 section, are briefly described and illustrated.

Proventricular trituration in adult carabid beetles (Coleoptera: Carabidae)

Adult carabids that ingest particles of food have a muscular proventriculus lined internally with an intima that bears sclerotized projections. In experiments where six species of carabid were allowed to feed upon Drosophila, the average size of cuticular remains found in post-proventricular regions of the gut was generally significantly smaller than those in the crop. This reduction in size of cuticular particles is likely to be due to proventricular trituration rather than prolonged exposure to digestive secretions. There is no evidence that material is triturated by the proventriculus and returned to the crop, the main seat of digestion in carabids, so proventricular trituration is unlikely to enhance digestion. By crushing large, potentially abrasive, cuticular particles, the proventriculus may serve to protect midgut epithelial tissue.

Débris cuticulaires d'annelides associés aux scolé-codontes

A description and figuration of numerous cuticular remains found in palynological preparations, attached to Paleozoic scolecodonts. These cuticular remains are ornamented and descriptions of different types are given. Most of these types are found in the living species of Eunicaea, permitting some remarks on their functional role and systematic significance. The samples studied here originated in the Sahara and in France and their age extends from the Ordovician to the Devonian.

Revision of the eocene flora of southeastern north America.

The Lower Eocene floras of southeastern North America were first published as a comprehensive flora by E. W. Berry in 1916 and later revised by him in 1930. This flora is one of the largest and most completely studied Eocene floras in North America. However, reinvestigation, presently in progress, has resulted in several revisions. Improved methods of research, more detailed and inclusive study expanding into new areas of research, and the increased understanding that has resulted from continued study in previously established areas of research, as well as the recent remapping of important deposits and the continued collection of fossil material, have provided the tools and information necessary for this revision. The age of these deposits has been revised from Wilcox group (Lower Eocene) to Claiborne group (Middle Eocene) and the nature of the deposits may now best be considered to be leaf-bearing clays laid down in ancient oxbow lakes. Recent studies of the cuticular remains of some leaves and pollen indicate that the clay pits are not isochronous but span the range of time of the Middle Eocene.
 Work which has been completed indicates that at least 60% of the taxonomic relationships of fossil forms to modern families and genera published by Berry are incorrect.
 When the fine venation and cuticular remains of the leaves are examined the presence of several extant taxa which Berry reported cannot be substantiated. Some taxonomic revisions are proposed; some of the fossil leaves studied could not be assigned to any known taxa and may represent extinct forms. The evolution of the angiosperms in the early Tertiary is often misunderstood because of the excessive number of extant generic and family names that are applied to fossil leaves with little or no detailed analysis of the fine venation or cuticular features of either modern or fossil angiosperms.
 The use of taxonomic affinities, community structure, and foliar physiognomy in making palaeoecological interpretations of early Tertiary floras is mentioned and the climate during Middle Eocene time in western Kentucky and Tennessee is reevaluated. The climate appears to have been dryer and somewhat cooler than previous investigators indicated.

The growth of the harvest mite, Trombicula autumnalis Shaw.

1.Rearing. Larvae ofTrombicula autumnaliswere fed on young mice (about 8 days old); after 48 hr. at 25° C. they began dropping off fully engorged.The post-larval stages were reared individually in separate filter-paper cells. At room temperature, 100% R. H., the engorged larvae were actively mobile for about 6–12 days, and for 12–20 days at 30° C., 100% R.H., before entering a quiescent stage (the developing nymphal stage). The nymphs emerged after about 33 days at room temperature, and 25 days at 30° C., from the time the engorged larvae dropped off the host.Of the nymphs which developed to adults, four fed on a mixture of yeast, molasses, and agar plus chicken faeces; one fed upon the exuded contents of the eggs ofAëdes aegypti; and another fed upon a mixture of all the ingredients mentioned. Young and old nymphs ofTrombicula autumnalisappeared to be incapable of feeding upon intact insects' eggs; neither did they show any particular predilection for the exuded contents of insects' eggs offered as a soft mass, and only with some difficulty were they made to introduce this food into the gut. When chicken faeces were offered as food the nymphs did not feed upon it.A method of ‘forced feeding’ was adopted, that is to say, nymphs were placed upon or guided on to the periphery of the food mass provided. When a nymph moved away it was replaced upon the food, and the process was repeated until the nymph showed signs of introducing the food into the gut. Occasionally a nymph after being placed upon the food remainedin situand fed continuously for about 6–8 hr. until completely engorged.2.The post-embryonic forms. The features of the stages (the larva nymph and adult), are described with respect to their development and growth.The transition, or developing stages (the pre-nymph and pre-adult), are closed systems which resemble the pupal stage of a holometabolous insect. The developing mite is enclosed by the cuticular remains of the preceding mobile stage, and a second inner or intermediate cuticle. Large flattened cells of epidermal origin are present, usually lying against the inner surface of the intermediate cuticle. Emergence of the nymph and adult depends upon the combined effects of an active secretion, which causes a disintegration of the intermediate cuticle, and muscular exertion.3.Dimorphism. Two kinds of dimorphism are shown during the growth ofT. autumnalis; sexual dimorphism associated with size, and nymphal dimorphism depending on marked differences in body shape and in the length of the posterior setae.Both kinds of dimorphism are initiated at the beginning of post-larval life (beginning of nymphal development).The time which the engorged larva takes to settle is inversely proportional to the size of the post-larval stages; in other words, the amount of activity and accompanying usage of acquired food reserves before the engorged larva settles appear to govern the absolute size of the individual during post-larval life. There is an indication of small forms becoming male and larger ones female.Two types of nymph (referred to in this paper as α-type and β-type nymphs) were bred from out-wardly identical larvae. The differences in the growth of the body as a whole and the posterior setae, which distinguish the two types of nymph, appear to be of developmental origin.4.The life cycle in the natural environment. Laboratory findings confirm the view that only one generation is produced each year, but that successive broods are produced throughout the season of incidence.

Petrography of American lignites

The extensive deposits of low-rank coal in the United States are receiving more than usual attention as a result of declining reserves of competitively more favorable coals and the development of important nonfuel uses of coal. Use of domestic lignite for solvent extraction of montan wax to replace foreign supply cut off from American industry is an example.This paper describes briefly occurrences of lignitic coals in the United States and includes discussion of terminology, petrographic composition, coalification, and rank classification of these coals.Certain tests are described and data presented showing results of petrographic investigation of the source of wax and resin in lignite. Purpose of the investigation was to determine the components in lignite contributing to the solvent extraction products, and the phyteral source of waxy, resinous, and elements in the extracts.Certain varieties of attrital lignite proved to be the most important source material of waxy solvent extracts. Pure attrital lignite of known high solvent yield was broken down by a method of chemical maceration which removed humic matter and freed various ingredients of the attritus, mostly yellow translucent matter. Phyteral components in the residue were spores, pollen, particles of lump-type resin, round, light and dark bodies, dark resinous rodlets, remains of petioles and cuticular matter.A microscope hot stage was used to observe the effect of heat on these various ingredients and their solvent products. Information resulted which indicated that, for attrital lignites tested, the wax in solvent extracts is derived mainly from cuticular remains, resin from lump-type resin and round bodies, and asphaltic material probably from dark resinous bodies. The discovery of wax associated with cuticular remains is in keeping with the known fact that in living plants wax is found exclusively in cuticular coverings of leaves, petioles, and reproductive organs, and in suberin. Origin of attrital and xyloid lignites is discussed.