Two life positions of fossil naticid opercula are recognized in Pliocene deposits of Hokkaido, northern Japan. In one position, the operculum seals the aperture. In the other position, the operculum is pressed against the shell base adjacent to the aperture. The death position of the head-foot mass can be reconstructed from the two opercular positions, which coincide, respectively, to naticids that died with the head-foot mass retracted into the shell, and those that died with it entirely extended from the shell.

Examination, utilizing scanning electron microscopy, of 58 specimens of Hoploparia stokesi (Weller) from the Maastrichtian portion of the Lopez de Bertodano Formation, Seymour Island, Antarctica, leads to the conclusion that cuticular ultrastructure may be used to distinguish molted from deceased remains of nephropid lobsters. Molted cuticle is characterized by deterioration, or loss, of lamination in the inner endocuticle whereas cuticle, during the intermolt phase, exhibits lamination throughout the endocuticle as well as the exocuticle. Diagenetic effects may obscure lamination throughout the cuticle. These observations confirm that Salter's position is typical of molted remains in fossils. Furthermore, partial remains of H. stokesi generally are molts. Preservational quality of molted remains tends to be better than that of corpses.

The presence of large numbers of phragmocones of Eutrephoceras and Aturia in an upper Eocene beach deposit of the La Meseta Formation on Seymour Island is the first known occurrence of beach-drifted accumulations of nautilid shells in the fossil record and may also represent the first documentation of a mass stranding of nautilids in the Cenozoic.

Familial groupings of two upper Paleozoic superfamilies of Goniatitina, Marathonitaceae and Cyclolobaceae, are reviewed. It is concluded that the Marathonitidae gave rise to the Hyattoceratidae and together constitute the Marathonitaceae. Eohyattoceras n. gen. is the Lower Permian ancestral hyattoceratid, and is represented by two new species, the type, E. gerthi from the Roadian of Timor, and E. leei from the Sakmarian of Nevada. An advanced marathonitid from the Lower Permian (Roadian) of Timor is described as Cardiella martodjojoi n. sp.

Two lineages within the exclusively Permian family Cyclolobidae are recognized as the subfamilies Kufengoceratinae and Cyclolobinae. Type designations proposed herein fix usage of Demarezites Ruzhentsev (1955) as referring to ancestral Cyclolobinae, and D. oyensi (Gerth, 1950) and D. lidacensis (de Roever, 1940) are redescribed from the Lower Permian (Roadian) of Timor. The Cyclolobidae are derived from the Vidrioceratidae and together constitute the Cyclolobaceae.

A diverse cirriped fauna, including the scalpelloids Cretiscalpellum homseyi n. sp., Arcoscalpellum withersi Collins, Arcoscalpellum bakeri Collins, Virgiscalpellum gabbi heintzi n. subsp., Virgiscalpellum sp., V. cf. V. gabbi apertus Collins, and the brachylepadomorph Brachylepas solida n. sp., occurs in the Upper Cretaceous Mt. Laurel Sand at the Biggs Farm locality on the Chesapeake and Delaware Canal, New Castle County, Delaware. This fauna represents the Maastrichtian Virgiscalpellum Zone originally identified in the Ripley and Prairie Bluff formations of the eastern Gulf Coast.

Although enrollment has long been recognized as an important, perhaps advantageous, life posture in certain trilobites, some aspects of this phenomenon are poorly understood. Taphonomic evidence indicates that the preservation of enrolled trilobites is a two-stage process involving: 1) factors that evoked enrollment; and 2) depositional and geochemical factors that resulted in preservation of the trilobites in an enrolled condition.

The Alden Pyrite Bed, Ledyard Shale Member, Ludlowville Formation (Middle Devonian, Givetian) of western New York, a well-known stratigraphic marker bed, is formally described herein. This bed yields an extraordinary number of enrolled phacopine trilobites. This study suggests that trilobites, like certain modern arthropods, enrolled in response to inhospitable conditions, including environmental toxicity and/or rapid sediment influx. Frequency of occurrence data from the Alden Pyrite Bed and underlying and overlying beds of the Ledyard Shale indicate that the trilobites Greenops boothi (Green) and Phacops rana (Green) both enrolled in response to adverse conditions at the sediment-water interface. Prolonged adversity compelled the trilobites to remain, and eventually die, in an enrolled state. Rapid and deep burial within a fine-grained sediment precluded scavenger dismemberment and favored geochemical conditions which culminated in pyritization and preservation.

The Florena Shale (Permian, Wolfcampian) of the Midcontinent of North America was deposited in a restricted marine basin. Shifting environments due to marine regression caused a gradual change in the ostracode fauna. Cluster analysis and ordination by nonmetric multidimensional scaling of data on ostracode relative abundances revealed three ostracode assemblages, each characteristic of a different environment. The Cryptobairdia seminalis assemblage from the lowest Florena Shale is characteristic of deeper water, offshore, marine environments with only minor influx of terrigenous mud. The Amphissites centronotus assemblage found above the C. seminalis assemblage occupied a similar environment, but with greater influx of terrigenous mud and intervals of increased turbidity. The Knightina texana assemblage occurs stratigraphically highest and probably represents a quiet-water, very shallow, nearshore, marine environment. Although protected from strong wave and current activity, the water mass was occasionally turbid.

Species diversity of ostracodes is high both at the base of the Florena Shale, which was deposited in the most offshore position, and again at the top of the lower part of the Florena Shale, which was deposited nearer to the shore. In contrast to diversities of assemblages of ostracodes from similar environments in other stratigraphic units, the K. texana assemblage has an anomalously high diversity. This is due in part to time averaging of adjacent ostracode assemblages and a strong taphonomic overprint.

Spirodentalium Walcott, 1890, was originally described as a scaphopod. A reinterpretation of the type lot suggests that its overall shape is that of an open-coiled gastropod. If so, this is probably the earliest known open-coiled form and it is sinistral in coiling direction.

Lower Carboniferous (Viséan-?early Namurian) conodonts, and some of their variably complete reconstructed apparatuses, are described from cyclic marine carbonates, associated with evaporites and mud rocks, of the Windsor Group, Magdalen Islands, Quebec, Canada. The conodont fauna includes Clydagnathus windsorensis, Cavusgnathus unicornis, Taphrognathus transatlanticus, Hindeodus cristula, Hindeodus? scitulus, Vogelgnathus campbelli, Ozarkodina laevipostica, Mestognathus bipluti, Mestognathus spp., Spathognathodus? n. sp. A, and Apatognathus spp.

Calceocrinids are unique crinoids with the crown movably hinged to a recumbent stem. The crown was raised for feeding by closing the hinge and bending the proximal stem. While resting, the crown lay parallel to the stem with the hinge opened. Allometric equations for four species reflect a combination of ontogeny, adult body size, phylogeny, habitat, and functional morphology. The hinge of most adult calceocrinids is extended into ear-like projections which made the crown more stable on the seafloor. For the hinge moment versus the effective weight of the crown, positive allometry characterized taxa that lived in agitated environments, whereas isometry was adequate for quiet-water species. The adult body size provides a secondary effect on the data for crinoids from the same type of environment. Here, the initial intercepts are transposed so that larger animals functioned like smaller ones. The equations are independent of phylogenetic position. All species exhibit positive allometry of the length and number of plates in the arms. The food-gathering capacity of a crinoid is estimated by the number of food-catching tube-feet multiplied by the width of the food grooves, whereas the soft parts that must be fed are proportional to the crown volume. The ratio of food-gathering capacity to crown volume is either fixed or decreases slightly in larger crinoids. Statistical tests reveal that all species follow a single developmental pattern for these two parameters. However, some of the evolutionary changes in the arms permitted calceocrinids to retain an adequate food-gathering capacity into larger adult body sizes.

The fossilized gladii of six squid from the Pembina Member of the Pierre Shale (Upper Cretaceous, Campanian) of southern Manitoba are referred to Tusoteuthis longa Logan, 1898, a species previously reported only from the Niobrara Formation of Kansas. The characters used to identify the genus are reviewed and it is referred to the family Kelaenidae. Documentation of these specimens extends the range of both the genus and the family to the Campanian of Canada.

A new calappid crab, Prehepatus werneri n. sp., is described from the Upper Maastrichtian of Limburg, The Netherlands. This species represents the first European and youngest known member of the genus. The appearance of this species seems to correspond with an increasing Tethyan influence in the type-Maastrichtian area.

Closterocrinus elongatus Hall, 1852, long assigned to the cladid inadunate crinoid family Ampheristocrinidae (=Euspirocrinidae), has been found to possess pinnulate biserial arms and a cup composed of four exsert basals, five radials, a primanal above the radial circlet, and fixed primibrachials and secundibrachials. Accordingly, this species is herein reassigned to the monobathrid camerate crinoid family Paramelocrinidae.

Four compsocrinine camerate crinoids are described from the Lower Silurian Brassfield Formation of southwestern Ohio. These late early or early middle Llandoverian crinoids are assigned to the Periechocrinidae and include Tirocrinus trochos n. gen. and sp., Ibanocrinus petalos n. gen. and sp., Acacocrinus anebos n. sp., and the taxon Dimerocrinites? vagans Foerste, herein referred to periechocrinid incertae sedis.

These Brassfield forms are the oldest known members of the Periechocrinacea and Periechocrinidae. Diagnoses of these supergeneric concepts are broadened to include the morphologic variability embodied within the Brassfield forms but not otherwise present in later periechocrinaceans.

A fauna of disarticulated Devonian fossil fish remains includes osteolepid, palaeoniscoid, acanthodian, placoderm, and possible agnathan material. Lithologic and biostratigraphic evidence for a lacustrine or paludal environmental interpretation is examined. Palynomorphs from the deposit suggest a Middle (Givetian) to early Late (Frasnian) Devonian age which is compatible with the faunal evidence.

The Lower Cambrian sequence south of the town of Caborca in northwestern Sonora, Mexico, has yielded the trilobites Nevadia ovalis n. sp. and Judomia orbis n. sp., plus an incomplete fallotaspid cephalon. The Nevadella Zone of Fritz (1972) can now be recognized in the Puerto Blanco Formation, and fossils from the middle part of the formation strongly suggest the presence of the Fallotaspis Zone. The new fossils permit improved correlation of the Mexican sequence to sections in the United States and to Lower Cambrian stages of China and the Soviet Union.

Seven previously described and seven new taxa of gyrodiform naticoids from West Coast Late Cretaceous–Paleocene age strata are discussed. Gyrodes (Gyrodes) dowelli White of Turonian age is a typical Gyrodes; G. robustus Waring from the Paleocene has the shape of Gyrodes s.s. but lacks the crenulations. G. greeni Murphy and Rodda, G. yolensis n. sp., G. quercus n. sp., G. banites n. sp., G. canadensis Whiteaves, G. pacificus n. sp., and G. expansus Gabb comprise the new subgenus Sohlella, which thus ranges from Cenomanian through Maastrichtian. Gyrodes robsauli n. sp. resembles “Polinices” (Hypterita) helicoides (Gray), and Hypterita is reassigned to the Gyrodinae as a subgenus of Gyrodes. Gyrodes onensis n. sp. of Albian age is similar to the G. americanus group of Sohl (1960). Three texa—Natica allisoni (Murphy and Rodda) of Cenomanian age and N. conradiana Gabb and N. conradiana vacculae n. subsp. of Turonian age—which have all been previously considered to be Gyrodes are placed in Natica. Well marked relict color patterns on N. conradiana and N. conradiana vacculae suggest that these naticids from northern California and southern British Columbia were tropical forms.

Diversity of taxa and size of specimens are reduced at the end of the Turonian, suggesting a change in West Coast marine conditions at that time.

Isorophid edrioasteroids representing a new genus and two new species are described from the Chesterian (Upper Mississippian) of Illinois and Maryland. Neoisorophusella lanei occurs in the Kinkaid Limestone of Johnson County, Illinois, and N. berryi occurs in the Greenbrier Limestone of Garrett County, Maryland. The problematic edrioasteroid species Hemicystites? carbonarius Bassler, 1935, from the Chesterian of southern West Virginia, is questionably assigned to Neoisorophusella.

Two recently collected specimens of Bogotacrinus scheibei Schmidt, 1937, from the Devonian (Emsian–Eifelian) Floresta Formation of Colombia reveal that Bogotacrinus is a dicyclic camerate crinoid genus closely related to Pterinocrinus Goldring, 1923 (Lower–Upper Devonian of eastern North America and western Europe), and Ampurocrinus McIntosh, 1981 (Lower Devonian of Bolivia). The new diplobathrid camerate crinoid family Pterinocrinidae, characterized by species with low conical dicyclic cups and rami composed of compound, bipinnulate brachials, is herein proposed to accommodate these three genera. This family originated in western Europe and migrated into the Malvinokaffric and southern Eastern Americas Realms during the Early Devonian and into the northeastern Appalachian Basin by the Late Devonian.

A new species of Brissus is described from the lower Oligocene (Rupelian–Vicksburgian) Bridgeboro limestone of southwestern Georgia. Brissus bridgeboroensis n. sp. most closely resembles the Recent Brissus unicolor (Leske) of the West Indies and the Gulf of Mexico, but it differs primarily in features of the posterior paired petals. Brissus bridgeboroensis is the oldest known member of the genus from continental North America.