The internal morphology of ambocoeliid brachiopods from the Middle Devonian Hamilton Group of western New York indicates a need for several taxonomic revisions. “Ambocoelia” praeumbona is transferred to Emanuella. “Ambocoelia” spinosa and “A.” nana represent Crurispina n. gen. Specimens of species belonging to Crurispina have moderately well developed crural plates, and, accordingly, they are assigned to the subfamily Rhynchospiriferinae. Crural plates are small and obscure but clearly present in Ambocoelia umbonata, the type species of Ambocoelia. Thus, the diagnosis of the subfamily Ambocoeliinae is emended to include species with tiny crural plates.

Ambocoeliid specimens from the Levanna Shale Member of the Skaneateles Formation, formerly referred to Echinocoelia, reveal several elaborate features in the pedicle valve, including an apical plate and a hollow tube supported by a median septum. These specimens represent a new genus and species, Mucroclipeus eliei. The homeomorphy found in the shape and size of these ambocoeliids may be the result of paedomorphosis. Additionally, their pattern of occurrence and minute size suggest that they attained their paedomorphic state through progenesis. The taxa Ambocoelia tuberculata n. sp., Crurispina n. gen., and Mucroclipeus eliei n. gen. and sp. are established.

Specimens of the gastropod genus Donaldina are numerous throughout marine units of the Pottsville, Allegheny, and Conemaugh Groups in the Appalachian Basin. Six species of Donaldina from thirteen marine units are described. New species proposed are Donaldina quadroliratus, from Pottsville and Allegheny units, and Donaldina superclivis, from Conemaugh units.

Three gastropod species are described from a previously unknown shallow-marine molluscan fauna in the lower Eocene Bateque Formation, southwest of San Ignacio, Baja California Sur, Mexico. Velates batequensis n. sp., a commonly occurring neritid in the Bateque, is the only ribbed Velates known from the Western Hemisphere. The fairly rare Platyoptera pacifica n. sp. is the earliest record of this strombid genus and its first occurrence on the west coast of North America. The very rare Cypraedia sp. is also the first occurrence of this cypraeid-like genus on the west coast of North America.

Modiomytilus n. gen. is described from Tertiary sediments exposed in the southwestern corner of Santa Cruz province (Argentina). This large mytilid is characterized by its ornamentation of strong comarginal undulations, its smooth ligamentary ridge, and its relatively large anterior adductor muscle. Two new species are assigned to it: Modiomytilus argentinensis n. sp., from the Centinela Formation (Miocene) south of Lago Argentino, and Modiomytilus mercerati n. sp., from the Río Turbio Formation (Eocene) in Sierra Dorotea. Although other species belonging to this new taxon and previously referred to Mytilus have been described from Tertiary sediments in the region, none are known so far from rocks of comparable age outside Patagonia.

Encrinurinae from the Ludlovian Brownsport Formation in west central Tennessee include Balizoma ramskoeldi n. sp., Fragiscutum glebale Campbell, 1967, and Mackenziurus sp. Balizoma ramskoeldi is most similar to Ludlovian species in England and Gotland. The discovery of F. glebale in Tennessee extends the geographic range of this species, known also from the correlative Henryhouse Formation in Oklahoma. Fragiscutum is an eastern/southern Laurentian endemic; Balizoma is of Wenlockian–Přidolían range, with its most widespread Euramerican distribution in the Ludlow. The stratigraphic range of Mackenziurus is extended into the Ludlow.

Eight species of brachyuran decapod crustaceans are recorded from coastal outcrops of Island Sandstone between Perpendicular Point and Punakaiki, Westland, New Zealand. The fauna consists of three raninids—Laeviranina pororariensis (Glaessner), L. keyesi n. sp., Lyreidus bennetti n. sp.; two portunids—Rhachiosoma granuliferum (Glaessner), Pororaria eocenica Glaessner; a goneplacid—Carcinoplax temikoensis n. sp.; and two majids—Leptomithrax griffini n. sp., Notomithrax allani n. sp. Together, they form the most diverse brachyuran assemblage yet described from New Zealand. The decapods are preserved in unusual elliptical masses, with their long axes typically parallel to bedding, containing superbly preserved cuticle often surrounded by well-formed fecal pellets, probably of decapod origin. The accumulations are interpreted to be mechanical concentrations within depressions produced by decapods or associated spatangoid echinoids. Although seven of the species have been recorded only from the Island Sandstone, Rhachiosoma granuliferum (Glaessner) is now known to occur in the correlative deep-water facies of the Kaiata Formation in North Westland, as well as in the Tapui Sandstone, North Otago (middle Eocene), and from coeval rocks at Snowdrift Quarry, southeast Otago. The raninids suggest comparison with congeneric forms from Snowdrift Quarry and the Tapui Sandstone, as well as with the La Meseta Formation, Seymour Island, Antarctica. Based upon associated foraminiferans, a Kaiatan–Runangan (late Eocene) age is assigned to this fauna. The occurrences of Carcinoplax, Leptomithrax, and Notomithrax represent paleobiogeographic and stratigraphic records for the genera.

The basal part of the Upper Cretaceous, mid-Campanian to Maastrichtian Izumi Group of the Izumi Mountains and Awaji Island, Southwest Japan, contains the most diverse gastropod fauna of this age in Japan. This paper discriminates 19 species and describes two new genera: Atira tricarinata n. sp., Ataphrus (s.s.) sp. A, Ataphrus (s.s.) sp. B, Globularia (s.s.) izumiensis n. sp., Lysis izumiensis n. sp., Trichotropis? sp., Deussenia takinoikensis n. sp., Volutilithes antiqua n. sp., Pseudoperissitys bicarinata Nagao and Otatume, Nekewis sp., Nipponitys inouei n. gen. and sp., Nipponitys acutangularis n. gen. and sp., Nipponitys sp. cf. N. magna (Kalishevitsch), Calorebama cretacea n. sp., Taniella japonica n. gen. and sp., Amuletum (s.s.) sp., Biplica osakensis n. sp., Biplica sphaerica n. sp., and Cylichna sp. The family Ampullospiridae is assigned to the suborder Architaenioglossa from the superfamily Naticacea. The enigmatic genus Lysis is tentatively assigned to the Calyptraeidae. Taniella japonica n. sp. is the oldest member of the family Olividae, and Calorebama cretacea n. sp. is the oldest member of the subfamily Pseudolivinae. Occurrence of Atira, Ataphrus, Biplica, and five perissityids further supports close communication of the northwestern Pacific Late Cretaceous gastropod faunas with those of the North American Pacific coastal areas.

Anomiid bivalves are abundant locally in a few beds of the Jetmore and Pfeifer Members (Turonian) of the Greenhorn Limestone of central Kansas. Our collection comprises nearly 500 whole and fragmentary specimens that are assigned to two new species, Anomia cobbani and A. pfeiferensis, based on external morphology and biometry. Occurrence of delicate Anomia valves in just a few beds of the Jetmore and Pfeifer reflects selective preservation that resulted from unusual taphonomic and diagenetic conditions rather than restricted stratigraphic and geographic range. Variations in curvature of the commissure and close association of Greenhorn Anomia with molds of small baculitid cephalopods suggest that these bivalves were epizoic on the baculitids. On the basis of close morphologic similarity, stratigraphic proximity, and geographic occurrence of the two new species, A. pfeiferensis n. sp. is believed to be the direct evolutionary descendant of A. cobbani n. sp.

Axiopsis eximia, a new species of thalassinidean shrimp, is described from an exposure of the Middle Eocene Lower Warley Hill Formation of South Carolina, U.S.A. Fossil axiids are rare, but this unique specimen is remarkably preserved as quartz free of enveloping matrix, having a nearly complete though distorted carapace, proximal parts of most thoracic appendages in situ but with distal articles missing, and extended abdomen with segments almost complete except for a few missing appendages. Presence of the bases of pleopods 1 and the elongate eyestalks surpassing the rostral apex, which it shares with the extant Axiopsis caespitosa group, place it provisionally in Axiopsis, which generally lacks first pleopods in males.

A new genus, a new subgenus, and five new species of pterioid bivalves are described from shallow-marine faunas in the middle lower to middle Eocene Bateque Formation in the vicinity of Laguna San Ignacio to about 105 km southward, Pacific coast of Baja California Sur, Mexico. Batequeus n. gen. is a medium-sized pectinid with equally convex valves, a short byssal notch, anterior auricles smaller than the posterior ones, the left valve with numerous very closely spaced radial riblets that show the imbricated growth lines very well, the right valve with about 30 low, flat-topped radial ribs that can be grooved, and intercalary ribs on both valves. It is only known from its type species, Batequeus mezquitalensis n. sp., which is from the middle Eocene part of the Bateque Formation. Spondylus batequensis n. sp., a very spinose species, is from the middle lower Eocene part of the Bateque Formation and is only the second reported Spondylus from the lower Eocene of the west coast of North America. Pycnodonte (Phygraea) pacifica n. sp., a species characterized by a radial sulcus that originates in the umbo area, occurs in both the middle lower and middle Eocene parts of the Bateque Formation. Phygraea has not been reported previously from the west coast of North America. Pycnodonte (Pegma) n. subgen. has a plicate left valve with a large attachment area (that can cover the entire valve) and a right valve that usually has an inflated smooth central area surrounded by plicate margins. It is only known from its type species, Pycnodonte (Pegma) bajaensis n. sp., which occurs in both the middle lower and middle Eocene parts of the Bateque Formation. Cubitostrea mezquitalensis n. sp., a strongly ornamented species, is from the middle Eocene part of the Bateque Formation and is the first occurrence of this genus from the west coast of North America.

Hollinacean and kirkbyacean ostracodes are rare to abundant components of the ostracode faunas in the Pennsylvanian marine units of the Appalachian Basin. The diversity of these two groups appears lower in the Appalachian Basin than as reported from the Eastern Interior Basin. Thirty-six taxa, nine hollinelliid and 27 kirkbyiid, are identified. Three new species, Amphissites (Amphikegelites) sohni, Kegelites cooperi, and Kirkbya causa, are proposed.

Kirkbyaceans from the Morrowan–Atokan portion of the section compare favorably with those described from the Eastern Interior Basin. The Shleesha rothi Zone of the Eastern Interior Basin can be recognized in the Appalachian Basin, comprising Morrowan and Atokan units. Desmoinesian units in the Appalachian Basin contain many taxa extending up from the Atokan, but several new forms appear. Of the latter, Kegelites cooperi is the most diagnostic species and is the name bearer for the Kegelites cooperi Zone. Missourian–Virgilian faunas are significantly different from those in the Desmoinesian, but are not separable from each other. These units are grouped together into the Kegelites dattonensis Zone.

Up to four discrete protaspid larval stages are described for calymenid trilobites of Ordovician to Devonian age. The earliest growth stages are nonadult-like planktonic protaspides; later protaspides are adult-like and benthonic. In contrast, the related homalonotid trilobites apparently lack planktonic protaspides, but have up to two large benthonic protaspid stages that are similar in form to calymenid benthonic protaspides. These differences in life history patterns between these families are reflected in their paleobiogeographic distributions. Calymenids werre widely dispersed from Ordovician to Devonian times, both being common in warm, low latitude provinces (particularly from the Late Ordovician onwards) and well represented in cooler, higher latitude regions. The paleogeographic distribution of the homalonotids during the Ordovician (Arenig to the Ashgill) was concentrated in high paleolatitudes, with only a few forms occurring at low paleolatitudes (often in deeper, cooler environments?). Both families survived the Ordovician–Silurian mass extinction, with the calymenids again being widely dispersed but the homalonotids being best represented in the cool-water Malvinokaffric Province and in other regions where they are largely restricted to clastic facies.

So few complete growth series of calymenine trilobites are known that it is unlikely that the ontogenies of taxa that form parts of ancestor–descendant clades can be identified. However, some evidence for heterochronic, particularly paedomorphic (neotenic), evolution is suggested for larval stages of members of both the Calymenidae and the Homalonotidae. Such possible neotenic evolution leading to very large planktonic larval stages of calymenid trilobites during the Devonian could have enhanced dispersal during a period of widespread warm and equable climates. Comparisons of homalonotid protaspides with equivalent stages of calymenids support the close relationship of these families within the Calymenina. A data matrix based upon characters of protaspides of two calymenine trilobites (Flexicalymene Shirley, 1936, and Brongniartella Reed, 1918) and eight other trilobites, belonging to the Phacopina (Calyptaulax), Cheirurina (Physemataspis and Hyrokybe), Proetida (Scharyia), Lichida (Acanthopyge), Odontopleurida (Diacanthaspis), Corynexochida (Bathyuriscus), and Ptychopariida (Crassifimbra) was subjected to cladistic analysis using the parsimony program “Hennig 86.” The shortest length cladogram produced is consistent with the inclusion of the Homalonotidae in the Calymenina, and inclusion of the Calymenina in the order Phacopida. “Cheirurina” is the paraphyletic “stem group” of Phacopina. The hypothesis that Lonchocephalidae is most closely related to part of post-Cambrian Phacopida is poorly supported by protaspid characters.

In Coal Creek Canyon, Utah, the Spring Canyon Member of the Blackhawk Formation is divisible into four regressive hemicycles of deposition, each representing the downdip part of a nearshore-to-offshore sequence. The first and fourth hemicycles are best developed. Individual bedding units span middle-shoreface to lower-offshore lithofacies, the latter corresponding to a thin intertongue of Mancos Shale.

Trace fossil assemblages include ~22 ichnospecies and 17 ichnogenera: Ancorichnus, Aulichnites, Chondrites, Cylindrichnus, Ophiomorpha, Palaeophycus, Phoebichnus, Planolites, Rosselia, Schaubcylindrichnus, Scolicia, Skolithos, Taenidium, Teichichnus, Terebellina, Thalassinoides, and Uchirites. Diversity and abundance of ichnospecies are greater in nearshore than in offshore lithofacies. Distal deposits are typified by obscure bioturbate textures: Cylindrichnus concentricus, Palaeophycus heberti, and Rosselia socialis are prevalent through the remainder of the lithofacies suite. Ophiomorpha irregulaire and Schaubcylindrichnus coronus are most common in middle-shoreface beds and Chondrites ichnosp. in upper-offshore beds; Ophiomorpha nodosa and O. annulata also are common in this part of the sequence.

The Ordovician diploporid Aristocystites Barrande lived recumbently on the seafloor but never evolved marginal frame plates or flexible tesselated surfaces. Flume studies on 1:1 scale models clearly indicate that this genus lived attached by an aboral holdfast with the aboral end of the theca facing into the current. The oral end, with its paired brachioles, fed in vortices generated in the lee of the theca. Optical current velocities for feeding probably ranged from 6 to 18 cm/sec. Growth of thecal plates and diplopore structures originated in galleried stereom. Secondary thickening occurred by growth of labyrinthine stereom. Aristocystites probably pressurized its gut as is suggested by the massive anal pyramid. Peristaltic waves through the gut would have enhanced body-fluid circulation and circulation through the diplopores. Aristocystites shows no signs of simplification in the ambulacral area. The transversely oriented, bilateral, ambulacral system is considered to be primitive. Other species synonymized with Aristocystites bohemicus Barrande from the Caradocian Zahořany Beds of Bohemia are A. desideratus, A. grandisculum, A. idealis, and A. rudis. Aristocystites metroi Parsley and Prokop, n. sp., is described from the upper Zahořany shale facies and the Bohdalec Formation from the Prague area.

Neoinoceramus Ihering, 1902, hitherto placed in the family Pernidae, is shown to be a member of the family Limidae, according to its edentulous hinge, well-defined ligamentary pit, and biauriculated shell. It was an epibenthonic bivalve living attached by a byssus to the hard substrate in a platform environment where some epibionts (muricaceous gastropods, sponges) were fixed on its shell.

Collections from the basal part of the marine Eocene Tejon Formation, Tehachapi Mountains, southern California, reveal new stratigraphic occurrences of patellogastropod limpets. Reports of these gastropods from California Paleogene strata are uncommon. The Tejon limpets are all members of the tropical genus Patelloida. Four taxa are represented in 33 specimens from five localities. These taxa include: mature specimens of P. tejonensis (Gabb, 1869), the first occurrence of the Eocene P. vokesi (Hickman, 1980) outside of Oregon, and P. triquetrus n. sp., described herein. Our study shows that a hypotype referred to P. tejonensis by Anderson and Hanna in 1925 is actually a fissurelloidean species, and we tentatively reallocate it to the genus Megathura Pilsbry, 1890. Analysis of depositional settings indicates that nearshore, shallow-subtidal depositional environments have higher patellogastropod abundance and diversity than intertidal or offshore-subtidal depositional environments. Morphological convergence between Tejon and Recent patellogastropod taxa is documented. Resemblance of the Eocene P. triquetrus n. sp. and an indeterminate Patelloidea sp. to the Quaternary “Collisella” scabra (Gould, 1846) and Lottia digitalis (Rathke, 1833), respectively, is remarkable.

The Early Carboniferous (Mississippian) cyathocrinine cladid crinoid Barycrinus, which is common in North America, has hitherto been recognized from Britain only on the evidence of one species, Barycrinus ribblesdalensis (Wright), based on rare dorsal cups. Barycrinus sp. pluricolumnals and plurimeres are common in the Salthill Cap Beds (Chadian), Salthill Quarry, Clitheroe, Lancashire, but are not conspecific with B. ribblesdalensis. Salthill ossicles are never preserved as individual columnals due to the relative weakness of the intermeric versus the longitudinal ligaments.

An ancestral paragastrioceratid, Svetlanoceras irwinense (Teichert and Glenister, 1952), and a specifically indeterminate gonioloboceratid, cf. Mescalites sp., from the basal Callytharra Formation are described as the oldest ammonoids recovered from the Permian of the Carnarvon Basin, Western Australia. Identity of these taxa strengthens correlation with the Holmwood Shale (Sakmarian) of the adjacent Perth Basin. Svetlanoceras moylei Mikesh, n. sp., from the Lenox Hills Formation of West Texas, is described for comparison with other simple paragastrioceratids.