Rare Specimens Research Articles

ANNOTATED LIST OF FISHES REPORTED FROM THE MARINE WATERS OF NEW YORK

The marine waters of New York State (excluding the Hudson River) are home to a large and diverse ichthyofauna that includes pelagics, migratory coastal fishes, resident species, anadromous and catadromous fishes, euryhaline-estuarine forms, and freshwater and deep-ocean strays. This diversity is attributable, in part, to the broad variety of habitats composing New York's marine waters. Also, although New York is located near the center of the Virginian biogeographic province, seasonal representatives of the Acadian and Carolinian provinces increase the breadth of its ichthyofauna. We record 338 fishes (114 families) reported from these waters, with annotations where warranted. Rare and unusual specimens are documented where possible with museum and literature citations.

Silurian bryozoans from Gotland fossilized in galena and sphalerite

Marls and limestones from the Lower Visby Marl of Gotland, close to the Llandovery/Wenlock boundary, contain rare specimens of bryozoans fossilized in galena or sphalerite. One species (possibly two) are mineralized by galena, and one by sphalerite out of about 20 bryozoan species (and many more species from other animal groups) in the same rock. The mechanisms of mineralization seem to occur in several stages, possibly involving microbial activity. The lead content of the sediment also seems to be extremely high. These observations raise taphonomic, palaeontological, sedimentological and geochemical problems, which are discussed: 1) the origin of the lead (ordinary sea water?), 2) origin of the high metal (especially lead) content of the rock (accumulation through green algae?), 3) the mechanism of mineralization through replacement of the bryozoan skeletal calcite (involving changes in pH, and other processes in the pore water?) and 4) why galena was only deposited on one (or two) species and sphalerite in another (nucleation initiated by microbes on species specific matrix proteins?).

Ｉｎｃｏｎｅｌ ７１８鋳造合金の溶接性に関する研究 ７ ＨＡＺ割れ感受性に及ぼす希土類元素の影響

A study was carried out to determine the effect of rare earth metal (La, Ce) addition on the HAZ cracking susceptibility of cast alloy 718 welds. The cast alloy 718 containing rare earth metal was melted in an alumina crucible heated in ambient argon by an induction generator and then poured into a copper mold. The contents of La and Ce addition were varied from 0 to 0.7 mass%. HAZ cracking susceptibility of the La and Ce-added cast alloy 718 in TIG and laser welds were evaluated by using self-restraint U-type hot cracking test and bead-on-plate test, respectively. The values of grain size and aspect ratio of grain in the La, Ce containing specimens were much less than those of rare earth metal-free specimens. Compared with the Ce-added specimen, the value of cumulative crack length was significantly lower for the La-added specimens. The La and Ce addition up to 0.3 mass% was found to have a beneficial effect to reduce the HAZ cracking susceptibility. Furthermore, no HAZ cracking was observed for the specimen containing 0.2 to 0.3 mass% La. However, when the amount of La and Ce addition exceeded 0.3 mass%, the HAZ cracking susceptibility contrarily increased.

Anatomy and three-dimensional reconstructions of the brain of a bottlenose dolphin (Tursiops truncatus) from magnetic resonance images.

Cetacean (dolphin, whale, and porpoise) brains are among the least studied mammalian brains because of the formidable challenge of collecting and histologically preparing such relatively rare and large specimens. Magnetic resonance imaging offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Furthermore, internal structures can be analyzed in their precise anatomic positions, which is difficult to accomplish after the spatial distortions often accompanying histological processing. In this study, images of the brain of an adult bottlenose dolphin, Tursiops truncatus, were scanned in the coronal plane at 148 antero-posterior levels. From these scans a computer-generated three-dimensional model was constructed using the programs VoxelView and VoxelMath (Vital Images, Inc.). This model, wherein details of internal and external morphology are represented in three-dimensional space, was then resectioned in orthogonal planes to produce corresponding series of virtual sections in the horizontal and sagittal planes. Sections in all three planes display the sizes and positions of major neuroanatomical features such as the arrangement of cortical lobes and subcortical structures such as the inferior and superior colliculi, and demonstrate the utility of MRI for neuroanatomical investigations of dolphin brains.

Land plants in the Devonian Villavicencio Formation, Mendoza Province, Argentina

Plant assemblages are described from two localities, San Isidro Creek and Vaqueria, in the marine basal Devonian Villavicencio Formation in Mendoza Province, the Argentine Precordillera. Abundant smooth and more rarely axes with enations occur with rare fertile specimens and isolated swollen structures interpreted as sporangia. Sterile ‘leafy’ axes are placed in a new morphotaxon, Bowerophylloides, and a new genus, Isidrophyton, has been erected to accommodate sterile axes with vertically elongate, fusiform surface features and terminal sessile sporangia borne in pairs. The plants are at similar grades of organisation to those in coeval assemblages elsewhere, but cannot be assigned unequivocally to existing taxa. The locations of these Lochkovian assemblages are plotted on basal Devonian palaeocontinental reconstructions and it is concluded that the composition and the isolated position of the Argentina assemblages on the western margin of Gondwana at mid latitudes in a possibly cool temperate climate hint at a distinct phytogeographic unit.

Magnetic resonance microscopy in cardiac development.

Magnetic resonance microscopy (MRM) is a fast and non-destructive imaging technique that can analyze the three-dimensional structure of the embryonic heart both qualitatively and quantitatively. Intravascular contrast agents have been developed to accentuate the anatomy of cardiac chambers, the cardiac outflow tract, and major arteries and veins throughout the embryonic body. MRM generates non-distorted three-dimensional data of vascular anatomy in a fraction of the time required by conventional optical image reconstruction techniques. The three-dimensional nature of these data allows the creation of visual models that can be manipulated for fast and easy interpretation of the complex relationships between heart chambers and aortic arches. This is particularly helpful because these relationships change in complex ways during development. The non-destructive nature of MRM makes it well suited for investigating rare or valuable specimens and live subjects. MRM techniques have been developed for imaging the embryo in utero and in vitro, although MRM studies of fixed embryo specimens are easier to perform and produce data with better contrast and higher resolution.

Pathology of Human Malignant Mesothelioma. Preliminary Analysis of 1,517 Mesothelioma Cases.

The author reviewed 1,517 human malignant mesothelioma cases from 1975 through August 2000. These mesothelioma cases were definite or probable in diagnostic certainty. Sources of these cases varied including asbestos insulation workers, UNARCO workers, Cancer and Leukemia B mesothelioma panel cases and random cases. Pathology materials consisted of autopsy, biopsy and rare cytology specimens. 92.3% of these patients were male, and 85.8% were between 50 and 79 years in age. The major primary site of the tumor was the pleura (73.1%). However, in a group of the asbestos insulation workers, the peritoneum was the more common primary site of malignant mesothelioma, compared to the pleura. Histologically, epithelial cell type was the majority (61.1%), followed by biphasic (22.1%) and fibrosarcomatous (16.4%). A double primary tumor (malignant mesothelioma associated with other cancer) was present in 32 of the 1,517 cases. These 32 cancers included lung cancers, renal cell carcinomas, colorectal cancers, pancreatic cancers and a cancer of the larynx, which are known to be at higher risk among asbestos insulation workers. The latency period of the vast majority (98.1%) of these mesothelioma cases were longer than 20 years. It is well accepted that cigarette smoking does not contribute to the induction of malignant mesothelioma. Indeed, the present study confirmed that 19.9% of these mesothelioma patients had never smoked cigarettes.

Ginandromorfo de Arsenura armida (Cramer) de Querari, São Gabriel da Cachoeira, Amazonas, Brasil (Lepidoptera, Saturniidae, Arsenurinae)

The occurrence of a rare ginandromorph specimen of Saturniidae collected in the State of Amazonas, Brazil is reported. This is the first unique deposit of a gynandromorph in the Collection of the National Institute for Amazonian Research.

Foraminifera, sequence stratigraphy and regional correlation; an example from the uppermost Albian of Southern England

While the general principles of sequence stratigraphy are well-established, the detailed distribution of fossils within sequences is less well known. Emery & Myers (1996) indicate that the most distinctive palaeontological information comes from the Maximum Flooding Surface where diverse assemblages, often dominated by planktonic taxa, are characteristic. The palaeontological features of a number of sequences in the uppermost Albian of Southern England have been documented in order to provide detailed palaeontological information on the distribution of foraminiferal taxa within the different systems tracts ( Van Wagoner et al., 1988 ). Within the uppermost Albian in Southern England the Gault Clay Formation presents a well-known succession of marine strata containing abundant Foraminiferida and other microfossils. The ammonite stratigraphy is also well established. Using coastal and borehole sections at Folkestone, samples from cored material recovered prior to the construction of the Channel Tunnel as well as samples from the construction phase, it has been possible to provide a detailed analysis of the uppermost Albian. This includes information on a little known cycle of sedimentation (“Zone 6a”) which is located between the uppermost Gault Clay Formation and the Glauconitic Marl (of Cenomanian age), but which is only known from the area of the Channel Tunnel. In S.W.England coeval strata contain fewer smaller Foraminiferida and other microfossil groups but do contain ammonites and large numbers of orbitolinids [large Foraminiferida]. The correlation of this sequence across the whole of Southern England is presented. Planktonic Foraminiferida (mainly hedbergellids) show a concentration in the Transgressive Systems Tract and around the Maximum Flooding Surface with fewer individuals being recorded in the Highstand Systems Tract. Specimens of Globigerinelloides bentonensis (MORROW), although present throughout, are very much larger around the level of the Maximum Flooding Surface and are associated with a reported occurrence of keeled rotaliporids and planomalinids, together with rare specimens of radiolaria. The benthonic Foraminiferida also show variations through the various systems tracts, especially in S.W.England where specimens of Orbitolina are commonly found associated with a major flooding event in the marginal marine sediments of the area.

Sexual reproduction of Cinachyra tarentina (porifera, demospongiae)

The sexual reproductive cycle of the Tetractinomorpha Spirophorida Cinachyra tarentina was studied mainly using light microscopy on samples collected in South Italy over a 2‐year period. Some aspects of the egg morphology were observed using transmission electron microscopy. Each year, young oocytes in pre‐vitellogenesis appeared in May and coexisted with growing oocytes. Yolk‐filled eggs were present in June and July. Oogenesis preceded spermatogenesis which occurred only in June. Cinachyra tarentina is an oviparous species having small eggs ranging from 40 to 50 pm in diameter which are scattered in the mesohyl and have a nucleolated nucleus surrounded by dictyosomes of the Golgi apparatus. Growing oocytes and yolk‐filled eggs have an irregular surface because of the presence of numerous pseudopodia which protrude into the mesohyl. Even though apparently gonochoric individuals were mostly observed, the rare specimens with sperm clusters and young oocytes proved the occurrence of successive hermaphroditism as an underlying mechanism. Some aspects of the reproductive biology of C. tarentina are compared with that of other Tetractinomorpha.

GRANITO POJUCA, SERRA DOS CARAJÁS (PA): COMPOSIÇÃO MINERALÓGICA, QUÍMICA MINERAL E CONTROLES QUÍMICOS DA ALTERAÇÃO HIDROTERMAL

The Pojuca granite is one of the intrusions formed during the anorogenic acid magmatic event that occurred in the Carajas Ridge region around 1.9 Ga. With a small outcropping area, it extends laterally under the Archean Igarape Pojuca Group host rocks. Petrographic studies combined with microprobe mineral data allowed not only a more accurate determination of the phases but also the identification of rare specimens. The Pojuca body presents leuco- to hololeucocratic rocks with mafic mineral contents that seldom are higher than 5% . Alkali-feldspar granites with subordinate syeno- and monzogranites are the rock types described. Albite, potassic feldspar and quartz are the main mineral constituents, whereas biotite, allanite and hornblende, in this order of abundance, are the varietal phases. Among the primary accessory minerais occur zircon, apatite, titanite, thorite/uranothorite, policrase, and microlite. Topaz is uncommon, although it and tourmaline appear to denote the transition between the pneumatolitic and the hydrothermal stages. About 30 secondary phases have been identified, many of them with a large composition variation. A few have equivalent counterparts in the primary assemblages as to indicate that the aqueous solutions and the granitic rocks approached an overall equilibrium. Several minerais, however, resulted from local equilibria in which the destroyed mineral or the fluid compositions were decisive for their formation. Ca-, Y- and REE-rich minerais (hellandite, gadolinite, synchisite, caysichite?) stand out in the hydrothermal assemblages and their common occurrence in veins/veinlets implies a significant mobility of those elements in the Pojuca system. As the REE distribution patterns in both primary and seconday minor phases are very similar, it seems very convincing that igneous accessory minerais were the major source for the lanthanides. Likewise, they probably were also the source for yttrium especially allanite (0,11-0,82% Y 2 O 3 ) and policrase (18,15% Y 2 O 3 ). Regarding calcium, it is suggested, on the basis of mass balance calculations, that the host amphibolites might have provided most of it to account for the observed amounts of hydrothermal Ca-rich minerais.

GRANITO POJUCA, SERRA DOS CARAJÁS (PA): COMPOSIÇÃO MINERALÓGICA, QUÍMICA MINERAL E CONTROLES QUÍMICOS DA ALTERAÇÃO HIDROTERMAL

The Pojuca granite is one of the intrusions formed during the anorogenic acid magmatic event that occurred in the Carajás Ridge region around 1.9 Ga. With a small outcropping área, it extends laterally under the Archean Igarapé Pojuca Group host rocks. Petrographic studies combined with microprobe mineral data allowed not only a more accurate determination of the phases but also the identification of rare specimens. The Pojuca body presents leuco- to hololeucocratic rocks with mafic mineral contents that seldom are higher than 5% . Alkali-feldspar granites with subordinate syeno- and monzogranites are the rock types described. Albite, potassic feldspar and quartz are the main mineral constituents, whereas biotite, allanite and hornblende, in this order of abundance, are the varietal phases. Among the primary accessory minerais occur zircon, apatite, titanite, thorite/uranothorite, policrase, and microlite. Topaz is uncommon, although it and tourmaline appear to denote the transition between the pneumatolitic and the hydrothermal stages. About 30 secondary phases have been identified, many of them with a large composition variation. A few have equivalent counterparts in the primary assemblages as to indicate that the aqueous solutions and the granitic rocks approached an overall equilibrium. Several minerais, however, resulted from local equilibria in which the destroyed mineral or the fluid compositions were decisive for their formation. Ca-, Y- and REE-rich minerais (hellandite, gadolinite, synchisite, caysichite?) stand out in the hydrothermal assemblages and their common occurrence in veins/veinlets implies a signifïcant mobility of those elements in the Pojuca system. As the REE distribution patterns in both primary and seconday minor phases are very similar, it seems very convincing that igneous accessory minerais were the major source for the lanthanides. Likewise, they probably were also the source for yttrium especially allanite (0,11-0,82% Y 2 O 3 ) and policrase (18,15% Y 2 O 3 ). Regarding calcium, it is suggested, on the basis of mass balance calculations, that the host amphibolites might have provided most of it to account for the observed amounts of hydrothermal Ca-rich minerais.

Paleochordodes protus n.g., n.sp. (Nematomorpha, Chordodidae), Parasites of a Fossil Cockroach, with a Critical Examination of Other Fossil Hairworms and Helminths of Extant Cockroaches (Insecta: Blattaria)

Two hairworm parasites of a cockroach in Dominican amber (15-45 mya) are described as Paleochordodes protus n.g., n.sp. (Nematomorpha, Chordodidae) and represent the first unequivocal record of fossil nematomorphs. Previous reports of putative nematomorphs are discussed and shown to be tentative at best. A critical examination of supposed mermithid nematode infections of cockroaches concludes that none of these can, at present, be confirmed. Worms arise from the fat of roaches Pliny the elder, Natural History, Chapter 6 (AD 77) Nematomorpha comprises a group of invertebrate parasites that are unique in many aspects (Poinar 1991 a,b). Literature dealing with fossil nematomorphs is rare and consists only of reports by Voigt (1938) and Xianguang & Bergstrom (1994), both of which are critically examined here and found to be tentative. A piece of amber from the Dominican Republic was discovered to contain two hairworms, one partly and one fully emerged from their cockroach host (Fig. 1). These rare specimens are described below in a new genus and species and a synopsis of the helminth fauna of extant cockroaches is presented.

An investigation of dolphin neocortex using computed tomography and magnetic resonance Imaging

The value of the conventional medical imaging applications of Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) to areas such as medical diagnosis and surgical planning are widely documented; however, less conventional uses also exist for such technology. This paper documents an example of the diverse, interdiscipl inary value of neuroradiological techniques such as CT and MRI. An assumption has been made, in the absence of data for dolphins, that the uniquely high relative neocortex volume in primates is responsible for setting them apart from all other orders of mammals, in terms of social intelligence. An investigation of dolphin brain structure was undertaken to verify or dismiss this assertion using three species ofdiffering social structure: sol itary humpback (Sousachinensis), social bottlenose (Tursiops truncatus) and gregarious common (Delphinus delphis) dolphins. CT provided good quality images for calculation of cranial volume but only permitted gross imaging of the supra- and infratentorial regions. MRI provided greater differentiation of the different brain regions, therebya"owing volumetric measurements of the neocortical region for all subjects. There was no significant difference in neocortex calculations from fresh and frozen material, suggesting that this technique may be used on rare specimens which are frozen before examination by biologists. Correlation of neocortical development with group size was significant (pO.OOl ).

Faunal dynamics and microevolutionary investigations in the Upper Cambrian Olenus Zone at Andrarum, Skåne, Sweden

The Upper Cambrian Homagnostus obesus/Olenus Biozone is well exposed in the old quarries at Andrarum, and is typically represented by unfossiliferous black shales with fossiliferous carbonate concretions. Near the north end of the “Great Quarry”, however, the shales themselves are replete with fossils, and in these a 1.8 m section has been logged to establish how trilobite populations fluctuated through time. Successive bedding planes were examined, at 1-cm intervals where possible, and for each surface trilobite exuviae, with rare complete specimens, were counted within a 5×5 cm quadrat. Olenus and Homagnostus are very common, but their abundance fluctuates dramatically; they co-occur in the upper part of the sequence but are otherwise almost mutually exclusive. This suggests that they had different ecological requirements. The rare Glyptagnostus and the bradoriid “ostracode” Cyclotron are confined to particular levels; the latter genus is found where no other fossils are present and may have been tolerant of very low oxygen levels. Eight horizons or bands are defined, based upon occurrence and abundance of the faunas; these bands are sometimes separated by clays, possibly relics of storm events. The logged section partially overlaps with that of Kaufmann. In our shale succession, Olenus truncatus, O. wahlenbergi and O. attenuatus are present in sequence, and the lengthening and narrowing of the pygidium, and the development of lateral spines in O. attenuatus as recorded by Kaufmann, are confirmed.

Cocoon-like trace fossils from the lacustrine-palustrine Bembridge Limestone Formation (Late Eocene), Southern England

In exposures of the Late Eocene Bembridge Limestone Formation at the west end of the Isle of Wight, calcareous ovoid-cylindrical trace fossils, ranging in length from 1 to over 47 mm long, but commonly 30 mm long and 15 mm in diameter, occur sparingly distributed in freshwater to pedogenically-modified limestones yielding calcitic casts of freshwater snails and land snails. Although specimens of the trace fossils having both ends entire are usually preserved as calcitic to calcite internal casts, the occurrence of rare hollow specimens lined by drusy calcite is evidence that they were chambers within the sediment. The majority of specimens were ruptured sub-terminally at one end before fossilization, probably by the escaping organism. Such specimens are partly to entirely filled by intraclastic lime mudstone. Rare specimens are attached to a short burrow-fill composed of similar lime mudstone and about the same diameter as the chamber. Most chambers have a surficial film of chalky micrite or microspar, with or without a cemented surficial micritic skin. In some specimens the micritic skin protects a surface ornament of lobate and composite tobate-linear ridges 0.5 mm wide and up to 5 mm long. When weathered-out in relief, these impart a wrinkle-like or fibrous surface texture, which can have a distinct helical trend. Whereas hitherto the chambers have been interpreted as tropical land snails' eggs, they differ from the latter in shape, surface texture, mode of rupture and mode of occurrence. The chambers also lack an egg-shell microstructure and cannot be reptile eggs. Although some analogous foreign specimens have been interpreted as simple hymenopteran brood chambers, fossil and Recent examples of these have a distinct terminal cap or seal, lacking in the Bembridge Limestone specimens. Instead, they may have been made by other kinds of insect for pupation, or by an unknown organism for aestivation or hibernation.

Technical note: CT determination of the mineral density of dry bone specimens using the dipotassium phosphate phantom.

Recent studies have demonstrated the potential application of computed tomography (CT) in research into bone density. Clinical studies of bone density using CT commonly employ a dipotassium phosphate phantom to calibrate measurements of mineral density. Designed for in vivo studies, the use of this phantom requires that bones be scanned while immersed in and permeated by fluids or soft tissues similar to water in X-ray attenuation coefficient. However, this condition may not always be met in anthropological applications, which often involve rare and fragile specimens. This study compares mineral density values calculated for a sample of bones scanned-at the same sites-in air and in water. The results indicate that, when scanned in air, the mineral density of trabecular bone is dramatically underestimated, while that of cortical bone is slightly overestimated. We present a linear regression equation to correct this error but recommend that, when possible, researchers calculate their own regressions based on their specific scanning conditions.

Technical note: CT determination of the mineral density of dry bone specimens using the dipotassium phosphate phantom

Recent studies have demonstrated the potential application of computed tomography (CT) in research into bone density. Clinical studies of bone density using CT commonly employ a dipotassium phosphate phantom to calibrate measurements of mineral density. Designed for in vivo studies, the use of this phantom requires that bones be scanned while immersed in and permeated by fluids or soft tissues similar to water in X-ray attenuation coefficient. However, this condition may not always be met in anthropological applications, which often involve rare and fragile specimens. This study compares mineral density values calculated for a sample of bones scanned-at the same sites-in air and in water. The results indicate that, when scanned in air, the mineral density of trabecular bone is dramatically underestimated, while that of cortical bone is slightly overestimated. We present a linear regression equation to correct this error but recommend that, when possible, researchers calculate their own regressions based on their specific scanning conditions.

Beidellite and Associated Clays from the Delamar Mine and Florida Mountain Area, Idaho

AbstractThere has been much interest in the rare specimen of beidellite from the Black Jack Mine, Florida Mountain, Idaho. A variety of aluminous clays exists along veins such as the Black Jack vein, in rhyolite and latite flows, and in near-surface ash beds, often containing less than 1.0% MgO and 0.5% Na20. Associated clays include beidellite, illite, kaolinite, 10-Å halloysite, dickite, nacrite, rectorite and a tarasovite-like mineral. The predominant clay is mixed-layer illite—beidellite. The beidellites have Al2O3 contents ranging from about 28 to 33%, and predominantly Ca and K as interlayer cations. The typical beidellite dehydroxylation temperatures of about 595 °C readily differentiate the beidellite from montmorillonite, which has a dehydroxylation temperature in the range of 735 °C. A modified differential thermal analysis (DTA) method is given for readily estimating the interlayer cation populations of smectites, including Mg++ and Al+++ cations. Chemical analyses and layer charges of II beidellites from mines around the Black Jack Mine are given. The beidellites have an American Society for Testing and Materials (ASTM) classification of CR, φ value, internal friction angle of about 8° and an expansion pressure of about 9 kgf/cm2 (88.3 kPa), similar to that of nontronite.

Les mammiféres insectivoresdes nouvelles collections de Sossís et sites associes (Éocène supérieur, Espagne)

New collections from Soss/'is s.l. localities (Late Eocene, NE Spain) provide data on apatemyid and nyctitheriidinsectivores. With regard to the former, a few isolated teeth are related to the Heterohyus (Chardinyus) nanus lineage. The evolutionary stage documented at Sossís stands in an intermediate position between those of Robiac (MP 16) and the MP 17b Quercy phosphorite faunas. With regard to nyctitheriids, numerous isolated teeth are related to a small species described as a new taxon, Euronyctia montana nov. gen., nov. sp. Rare specimens are referred to Saturninia pirenaica, hitherto known from Soss/'is, and some other insectivores previously reported from the locality are discussed. Euronyctia montana is interpreted as an intermediate evolutionary stage within a peculiar nyctitheriine lineage including the earlier grisollensis (MP 16) and the later tobieni (MP 19) species. These new data allow reassessment of various European Late Eocene nyctitheriids as well as the recognition of a new species among the Quercy representatives, Saturninia pelissiei. The dilambdodont condition of the cheek teeth attained by the Euronyctia lineage is discussed under functional, adaptive and ecological aspects. On the biochronological aspect, the new Sossís insectivore material, especially that of Heterohyus nanus, adds new and precise evidence to the correlation of the Sossís fauna with the Early Ludian faunas referred to MP 17a.