The purpose of this paper is to propose a chitinozoan zonation of the Ordovician of Quebec and western Newfoundland. On the basis of chitinozoan assemblages previously described from various sections, covering almost the entire Ordovician System, 22 biozones, based on first appearance of index species, are distinguished. As the strata from which the chitinozoan microfaunas were extracted are well dated by other fossils, especially graptolites, it is possible to establish a correlation between the chitinozoan and the established graptolite and conodont zonations of North America and Great Britain.

Proconchidium brodeurensis n. sp. occurs 212 m above the base of member B of the Baillarge Formation on Brodeur Peninsula, Baffin Island, 8 m below the Ordovician–Silurian boundary. Study of Proconchidium shows that it can be easily distinguished from Eoconchidium but possesses many characters that are similar to those in Tcherskidium. Analysis of internal structures suggests that the three genera can be distinguished from each other and belong to Virgianidae. Tcherskidiidae is a synonym of Virgianidae and should be abandoned.

This represents the first recorded occurrence of Proconchidium in North America. Although this genus and its related genera Tcherskidium Sapelnikov, 1972, and Eoconchidium Rozman, 1967, are common in Ashgill strata of Eurasia, they have not been recorded or illustrated from North America. This led to the suggestion that distinct brachiopod biogeographic provinces may have existed during the Ashgill. The occurrence of these genera probably indicates that they may have lived in mostly tropical and subtropical zones.

Watsonella crosbyi Grabau, 1900, a senior synonym of Heraultipegma varensalense (Cobbold, 1935) and H. yannense He and Yang, 1982, is the oldest known rostroconch. The species ranges through most of the Early Cambrian and has been recovered from temperate siliciclastic (Avalon Platform) and tropical carbonate (south China, Mongolia?, southern France) environments. Watsonella crosbyi occurs through approximately 880 meters of the sub-trilobitic Lower Cambrian of southeastern Newfoundland. Its lowest occurrence corresponds to the first appearance of relatively diverse small shelly faunas of the pre-Tommotian Watsonella crosbyi Zone (new).

The general form of Watsonella crosbyi conchs (laterally compressed, prosogyrate, elongate posterior, subdued comarginal growth lines, very thin shell with anterior and posterior gapes) is similar to that in a number of larger burrowing pelecypods, but this does not rule out other benthic habits. However, recovery of locally common in situ conchs (plane of commissure vertical, long axis subhorizontal) in the lower and upper parts of its stratigraphic range in southeastern Newfoundland corroborates an infaunal life habit for the species. The animal is a prominent element in faunas from offshore, cohesive, siliciclastic mudstones but also occurs in calcareous nodule-rich mudstones, shell hash limestones, and, infrequently, in peritidal algalaminate limestones. A phylogenetic sequence from laterally compressed monoplacophorans to early ribeiroid rostroconchs and leading to the oldest pelecypods was completed by the middle Early Cambrian and involved infaunal mollusks.

Inozoans are described from patch reefs on the carbonate platform of eastern Sichuan, from the uppermost Permian Laolongdong reefs in the Changxing Formation (Kazanian–Tatarian) at Beipei, northwest of Chongqing, and from Middle and Upper Permian reefs from the Maokou (Kungurian), Wujiaping (Ufimian), and Changxing Formations at Xiangbo, Longlin County, in northwestern Guangxi. Classification of inozoans, particularly late Paleozoic ones, is still in a state of flux, but genera recognized to date can be keyed using the general nature of the spongocoel, canals, and growth form.

New genera described are Intratubospongia, Grossotubenella, Cavusonella, and Radicanalospongia. The new species described are Stellispongia radiata, S. minor, Peronidella beipeiensis, P. regulara, P. parva, Intratubospongia typica, I. tenuiperforata, I. multisi-phonata, I. minima, Grossotubenella parallela, Cavusonella caverna, and Radicanalospongia normala. A Corynella that is not identifiable to species and a sphinctozoan-like inozoan(?) sp. A that has a fibrous-appearing internal skeleton but is poorly preserved are also described. Inozoans and other sponges are major frame-builders in the Permian reefs of South China and our fauna is one of the most diverse late Paleozoic assemblages described to date.

Environmental conditions affect both the character and variability of developmental patterns (=astogeny) within each of four species of Ordovician bryozoans. Regressions between pairs of stereological measurements for populations from both high-and low-diversity habitats differ significantly in 79 percent of all comparisons. Deviations from a rigid pattern of development, measured as dispersion from regression, were greater in species populations from low diversity settings in 77 percent of comparisons. Therefore, both developmental patterns and their variability differ intraspecifically along a diversity gradient in representatives of four bryozoan families. Additionally, dispersion values were larger in younger rather than older colonies in two species irrespective of diversity level, thus suggesting an age-related reduction in variation.

Changes in developmental trajectories indicate that colonies from low-diversity settings are generally paedomorphic relative to conspecific populations from high-diversity habitats. The heritability of these characters and developmental patterns, estimated using variance partitioning techniques, is greater in high-diversity associations. These findings suggest that character state modifications dependent upon astogeny, or a consequence of astogenetic modifications, are more heritable in high-diversity settings. However, if the environment can cause facultative heterochrony, the possibility of fixing such patterns in subsequent generations is increased, although the mechanism for accomplishing this is presently unknown.

Praehyalocylis cretacea (Blanckenhorn, 1889), a pteropod previously known only from upper Eocene to middle Miocene strata in Europe and Turkey, is reported for the first time in similar age rocks in the northwestern United States. Of the 238 specimens, most occur as molds and casts in concretions in deep-water deposits from the Keasey Formation in Oregon, and from the Quimper Sandstone, Blakeley Formation, Pysht Formation, and Astoria Formation of Washington. Praehyalocylis has not been reported previously from the Western Hemisphere.

Clio berglundi n. sp. and C. goederti n. sp. are reported from upper Oligocene to lower Miocene rocks in Washington. Eleven specimens were found mostly as internal molds in concretions in deep-water deposits of the Lincoln Creek, Pysht, and Astoria Formations of Washington. Cenozoic species of Clio have not been reported previously from the West Coast of the United States.

Reexamination of collections of North American Hyolitha reveals the presence of several new genera and several taxa previously known only from southeastern Europe and the Soviet Union. New representatives of the family Hyolithidae in North America are Doescherina clarki n. gen. and sp. from the Upper Cambrian of Montana and Grantitheca glenisteri n. gen. and sp. from the Lower Cambrian of New York. The geographic and stratigraphic ranges of Nevadotheca Malinky are extended by placement of Hyolithes excellens Billings from the Lower Cambrian of Newfoundland and H. princeps Billings from the Lower Cambrian of Quebec in that genus, and by the occurrence of the new species N. heckeli in the Upper Cambrian of Tennessee. Diversity within the Hyolithidae is further increased by the discovery of specimens representing a new genus in the Upper Cambrian of Alberta, but that genus remains indeterminate because those specimens are not well preserved.

The type lot of Hyolithes communis Billings from the Lower Cambrian of Quebec is here included under Nitoricornus Syssoiev, to which the species H. impar Ford from the Lower Cambrian of New York is also transferred. Morphology of specimens of Hyolithes quadricostatus Shaler and Foerste from the Lower Cambrian of Newfoundland requires placement under Holmitheca quadricostatus (Shaler and Foerste) and Novitatus mapesi n. sp., family Novitatidae, order Orthothecida. Formerly, Nitoricornus Syssoiev, Holmitheca Syssoiev, and Novitatus Syssoiev were known only from the Soviet Union. These occurrences extend their geographic ranges to North America. The first known representative of the family Pauxillitidae Marek in North America, Neopauxillites zlatarskii n. gen. and sp., extends the range of that family from the Ordovician of Czechoslovakia to the Lower Cambrian of Newfoundland.

Overall poor preservation of type specimens of Hyolithes americanus (Hall), H. gregarius (Meek and Hayden), H. primordialis (Hall), and H. welleri Roy precludes complete diagnoses of these species and confident assignment to genus. Hyolithes americanus and H. welleri are tentatively included under Grantitheca; the other species remain under Hyolithes with question. The names of these species should not be used for new material until better preserved topotypes become available for study.

A paleoecological study of the Point Loma Formation (Upper Cretaceous, southern California) resulted in the discovery of a new genus assigned to the gastropod family Aporrhaidae. The individuals recovered provide the basis for the designation of Teneposita n. gen. based upon T. laeva n. sp. Teneposita is characterized by two delicate labral digitations, a short opposing digitation, and elongate anterior and posterior canals. Teneposita laeva is one of the smallest aporrhaids yet described.

Many specimens of the conulariid Paraconularia magna (Ries) from the Tackett Formation (Upper Pennsylvanian, Missourian) of Oklahoma exhibit repaired or unrepaired injured exoskeletons. Scalloped, cleft, and embayed patterns are interpreted to be repaired sublethal damages produced by unknown events or organisms. Punctures, which are the first reported in conulariids, were not followed by exoskeletal repair and were probably lethal. Cladodont sharks are implicated as possible predators of P. magna because of a close correspondence in size and pattern between the dentition of some sharks and the punctures preserved in conulariid exoskeletons.

The brachiopod Pentamerus oblongus is especially abundant in the Lower Silurian Rytteråker Formation, which occurs widely throughout the Oslo region in southern Norway. Alternating thin limestones and shales typically occur in a shallowing-upward sequence ending in a massive grainstone often rich in tabulate corals and stromatoporoids. In the lower beds, colonization by pentamerid populations was enhanched by prior emplacement of an orthotetacean shell pavement over the clastic sea bed. Individual Pentamerus size decreases with increasing disturbance of populations or their fragmentation as lag deposits nearer the stratigraphic level of the massive grainstone. The frequency of specific storm events and the changing depth to the sea bed may be indexed according to the average size of pentamerid shells in a given population and the degree to which the population is disturbed. Preservation of prominent growth lines (assumed to be annual) suggests storms stirred the sea bed in deeper waters on an 8–10 year cycle. In shallower waters, storms more regularly disturbed the sea bed every 2–3 years. These data corroborate the interpretation that the Pentamerus community inhabited marine waters below fair-weather wave base, but still within reach of storm wave base.

Anthraconaia sp. occurs in the thin nonmarine interval that lies between the Upper Millersburg Coal Member and the Lower Millersburg Coal Member (Pennsylvanian, Desmoinesian) in Warrick County, Indiana. Specimens of Anthraconaia sp. resemble Anthraconaia that occur in Pennsylvanian and Permian rocks of the Appalachian Basin, but they differ slightly in size, form ratios, or both. Specimens were found in massive, nonfissile gray mudstone; buff-colored, laminated limestone (ostracodal biomicrite, wackestone); and platy black shale. The only statistically significant variation between shells from these different lithologies is that shells recovered from the limestone tend to be more ovate than shells from the other two lithologies. This contradicts the findings of previous investigations in which more ovate Anthraconaia were found in the more organic-rich sediments of a given stratigraphic sequence. This difference is probably caused by the lack of discernible change in energy level through the depositional history of the interval and suggests that changing energy levels may be more important to the control of the morphology of Anthraconaia than the level of organic carbon in the sediment.

By the end of the Cretaceous, the Clavagellidae (Mollusca: Pelecypoda) maintained a distribution that was marginal to the core-Tethys, occurring in both North America and the Old World. Traditional paleozoogeographic interpretation contends that the clavagellids then went extinct in the New World because no Cenozoic fossil or living clavagellids have been documented from the Western Hemisphere. This report describes the occurrence of Eocene clavagellids from the Ocala Group of peninsular Florida. The presence of these pelecypods in Upper Eocene strata is consistent with the large Tethyan faunal component already known from this unit and requires a reassessment of Tertiary zoogeographic patterns for the clavagellids.

Twenty-one species of corals and three species of spongiomorphs occur in a series of richly fossiliferous, molluscan-dominated beds with silicified bioclasts in the Upper Triassic Martin Bridge Limestone of Hells Canyon, Oregon. Two of these, Maeandrostylis grandiseptus and Recticostastraea wallowaensis are new species. Recticostastraea is designated as a new genus.

The fauna is early Norian and occurs in the island arc Wallowa terrane, one of many tectonostratigraphic terranes in western North America. Like other examples, it appears to have developed independently of the North American craton and to have links with Wrangellia. The fossil corals and spongiomorphs are para-autochthonous, occurring in a series of tempestite beds. They are interpreted to have inhabited a shallow-water carbonate platform that developed around a tropical island arc following cessation of volcanic activity. The corals and spongiomorphs are associated with abundant gastropods and a diverse epifaunal suspension-feeding bivalve fauna. Relative to the corals, branching spongiomorphs, Spongiomorpha ramosa, are more abundant and occur with relatively common branching, sheet to plate-like, colonial corals. Solitary corals are relatively rare. The associated bedded limestone includes a variety of shallow-water microfacies but throughout the Hells Canyon sequence, reef structure is absent.

Together, the 24 coral and spongiomorph taxa show mixed paleogeographic affinities with Upper Triassic faunas known only from alpine regions of the western Tethys (five species), the Pamir Mountains, U.S.S.R. (two species), and the island of Timor (one species). Five additional species are pan-Tethyan and exceptionally cosmopolitan, but 11 species (45.8%) occur only in displaced terranes. Of these, a significant component (six species) is endemic to the Wallowa terrane. At least four Hells Canyon taxa, previously thought endemic to North American terranes, have recently been reported from the high-latitude Koryak terrane of northeastern U.S.S.R., a displaced tropical volcanic terrane of the northwestern Pacific. For Triassic corals, this is the first example of a clear link between western Pacific and eastern Pacific terranes. Less similarity exists with the Wrangell Mountains, Alaska, where identical age lower Norian silicified corals and spongiomorphs are known.

Specimens representing Heliolites diligens Bondarenko, 1966, H. aff. H. luxarboreus Yang, 1978, and H. tchernyshevi Bondarenko, 1966, are common and Heliolites sp. and Stelliporella sp. are rare in diverse coral assemblages associated with lithistid sponge reefs in deep shelf or ramp limestone facies of the Douro Formation. Heliolites diligens, a more widely adapted, possibly “opportunist” species, occurs abundantly in lower diversity stromatoporoid/coral assemblages from nonreefal, shallower shelf limestone facies. Detailed systematic study of approximately contemporaneous populations of these Ludlovian heliolitid species shows that all are morphologically variable; assessment of this variability qualitatively and quantitatively is critical to species definition and recognition. Heliolites diligens is the most variable, with wide intercolony variation in septal development, corallite wall configuration, and spacing of horizontal skeletal elements. This apparently represents morphological plasticity rather than differences that can be ascribed to distinct species. Conspecificity of the more extreme and dissimilar variants can be inferred from study of large assemblages of coeval specimens. The other species, with more narrowly defined, discrete variation fields, are more readily distinguished from each other.

The benthic, free-living oyster Texigryphaea was the dominant constituent of many late Albian marine communities in the Texas and southern Western Interior regions. Large topotypic assemblages of three common lower–middle Washita Group species (T. navia and T. pitcheri in Oklahoma and T. tucumcarii in New Mexico) each display considerable morphological variation in valve shape and the proportions and expression of various features. Variation within an assemblage is partly due to ontogenetic changes but is mainly ecophenotypic, with local variation in nature of substrate, water turbulence, length of attachment time, and other factors influencing the final morphology of the mature shell. The T. navia assemblage is distinct in several important morphological characters from the other species, and the differences become more pronounced with growth. Texigryphaea navia appears to have been adapted to relatively firm substrates in moderately agitated conditions, in contrast to the other species, which occupied softer substrates in quieter environments. The essentially contemporaneous T. pitcheri and T. tucumcarii assemblages display much overlap in all measured dimensions of the left valve and in the range of intergrading morphs that compose each assemblage. Accordingly, T. tucumcarii is considered a synonym of T. pitcheri, representing populations of that species that lived in the West Texas-New Mexico area and developed only minor differences from the eastern populations. Within the T. navia topotypic assemblage are specimens intermediate between T. navia and T. pitcheri, and the eastern and western T. pitcheri assemblages contain forms apparently transitional to two other species, T. washitaensis and T. belviderensis. Ecophenotypic variation in the T. pitcheri assemblages appears to be greater than that in European Jurassic Gryphaea species and mirrors to some extent phyletic variation in European Jurassic Gryphaea lineages.

A single limestone slab is described from the Mississippian Bear Gulch Limestone of central Montana containing more than 100 bivalves, including Caneyella sp. and ?Ptychopteria (Actinopteria) sp., attached in original life positions along an 80-cm-long ?brown alga. The assemblage provides clear evidence of life position and choice of substrate for these pterioids. The bivalves increase in size, and appear to be radially disposed in their attachment sites, along the loosely coiled “kelp-like” alga, indicating little postmortem transport and current activity. The bivalve population is interpreted as living on an algal thallus that was either planktonic or attached to the substrate. Observations and comparisons with modern bivalve—seaweed associations support either view. Evidence for local anoxic conditions and stagnant water help explain the superb preservation and confirm past interpretations of the Bear Gulch Limestone.

Small gastropod opercula have been found at one locality each in the Desmoinesian and Virgilian of north-central Texas. Because of their general shape and concentric growth, these opercula are placed within the Neritacea. One form probably is the operculum of Trachydomia. Four other forms, two of which are morphologically quite similar but from different ages, probably belong with Naticopsis sensu lato.

A new genus, Calorebama, is proposed for a clade of pseudolivine gastropods (family Buccinidae) that has its earliest species in the lower Paleocene (Danian) of Alabama, its next earliest species in the upper Paleocene (Thanetian) of Alabama, and its subsequent species in the Eocene of California, Oregon, and Washington. Calorebama is characterized by an inflated biconical shape, a biangulate body whorl usually with strong nodes on the shoulder, and fine to medium spiral ribbing that is coarser anterior to the medial pseudolivine groove.

Previously, these pseudolivines now being placed in Calorebama were assigned to the genus Pseudoliva. Study of the literature and every available museum specimen showed Calorebama to have five species and two subspecies, all of which have biostratigraphic integrity.

Calorebama unicarinata (Aldrich) is the earliest species, and it, along with C. tuberculifera (Conrad), are the only known Gulf Coast species. Calorebama dilleri dilleri (Dickerson) is the earliest representative of the genus on the West Coast of North America, and it arrived during the early Eocene (Ypresian). Probable geographic isolation of C. dilleri dilleri in central and southern California resulted in lineage splitting and the appearance of C. dilleri lineata (Gabb), which phyletically evolved into C. inornata (Dickerson). Calorebama dilleri dilleri persisted in northern California and phyletically evolved into C. dilleri kirbyi (Clark), which similarly evolved into C. volutaeformis (Gabb).

Calorebama inornata and C. volutaeformis, the youngest species of the genus, became widely distributed along the West Coast of North America before becoming extinct by the end of the earliest late Eocene.

A new species of teuthid squid, Teudopsis cadominensis, is described from the Toarcian (Lower Jurassic) Poker Chip Shale of the Fernie Formation in central-western Alberta. Fossil squids are rare in the Mesozoic of North America; this species is the first record of the family Palaeololiginidae in North America and the first member of the suborder Mesoteuthina in the Jurassic of North America.

A new genus, Popenoeum, is proposed for a clade of Upper Cretaceous through lower Eocene pseudolivine gastropods found in North and South America, West Greenland, western Europe, and southern India. Popenoeum n. gen. is characterized by tabulate whorls with a prominent subsutural canal, collabral costae that terminate as tubercles on the body whorl shoulder, and closely spaced fine to strong spiral cords.

The type species, Popenoeum maritimus n. sp., is from the lower Paleocene (Danian) portion of the San Francisquito Formation, southern California, and from the upper Paleocene (Thanetian) Sepultura Formation, Baja California. Popenoeum maritimus bajaensis n. subsp. is also present in the Sepultura Formation.

Other species and subspecies in the clade include Popenoeum sp. (Toulmin) and P. scalina Heilprin from Alabama; P. mutabilis mutabilis (Woods) and P. mutabilis woodsi (Olsson) from northwestern Peru; P. aff. P. maritimus from West Greenland; P. brevis (Doncieux) and P. prima (Defiance) from France; P. chavani (Glibert), P. robusta (Briart and Cornet) and P. briarti (Vincent) from Belgium; and P. subcostata (Stoliczka) from southern India. The earliest species is P. subcostata, and it is the only Cretaceous species. The youngest form is P. mutabilis woodsi, and it is the only Eocene species. The new genus reached its peak during the Paleocene.