Intraspecific morphological variations have been investigated based on 1,090 specimens of a Pleistocene solitary scleractinian coral, Caryophyllia (Premocyathus) compressa Yabe and Eguchi. Special attention has been paid to variations in septal arrangements, septal numbers, insertion patterns of third-cycle septa, and pali. The specimens contain nine different septal plans from hexameral to decatetrameral, among which those having a decameral plan are the most common. There is a clear regularity in number and position of the third-cycle septa. Specimens in which the third cycle is incomplete are also considered to be mature forms. Number and position of pali are intimately related to the number and insertion pattern of the third-cycle septa. In extreme cases, there exist specimens having only two cycles of septa and lacking pali. Ninety-nine varieties in septal arrangements are considered to be present in the fossil population, although only 57 have been found in the collection. The present species includes many specimens which do not show bilateral symmetry.

Rousseauspira teicherti, a new genus and species of an unusual, untwisted, horn-shaped gastropod operculum from shallow-subtidal limestones of the Upper Ordovician of Alaska and the Middle Ordovician of California, is described and compared to two other Ordovician opercula, Ceratopea Ulrich, 1911, and Teiichispira Yochelson and Jones, 1968. The shell to which the operculum belonged is not yet known.

West Falls Group strata (Chemung facies) of Upper Devonian (Frasnian) age in New York State reflect sedimentation on a storm dominated sandy shelf. Rugose corals occur in storm deposited coquinites rich in bioclastic debris and are abundant locally, although representing only three species, Tabulophyllum orientale (Stumm), Macgeea ponderosa Stumm, and Disphyllum caespitosum (Goldfuss). The Tabulophyllum and Macgeea species are both characterized by large amounts of stereome (biogenic calcite) in the apical part of the corallite, perhaps useful in stabilizing corallites in the sediment.

The Wamp Spring section of the Bird Spring Group consists of approximately 1,600 feet of carbonate rocks subdivided into a basal platy limestone member, lower cliff-forming member, and upper cliff-forming member. Triticites, Schwagerina, and Schubertella kingi in the platy limestone member indicate an early Wolfcampian age. Schwagerina, Schubertella kingi, and a distinctive assemblage of brachiopods, similar to the West Texas fauna, including Kozlowskia kingi, Elliottella aff. E. multicostata, Leurosina sinesulca, Gypospirifer cf. G. infraplicus, and Composita cf. C. apheles, indicate that the upper cliff-forming member is late Wolfcampian. The lower cliff-forming member is tentatively assigned to the middle Wolfcampian. The Wamp Spring sequence correlates temporally with the BSe “formation” of the Bird Spring Group.

In addition to the previously mentioned taxa, the fossil-rich upper cliff-forming limestone member includes the new species Pontisia boodi, Crurithyris wampensis, and Calliprotonia(?) n. sp. A, as well as Hustedia culcitula, Crenispirifer(?) sp., Cenorhynchia(?) sp., Kutorginella(?) sp., marginiferids, lyssacine hexactinellid sponges, pleurotomarid and bellerophontid gastropods, cidaroid echinoids, rugose corals, cylindrical cryptostome bryozoans, and nuculids.

Septirhynchia hirschi n. sp. is described from the Callovian (Jurassic) strata of Gebel El-Maghara, northern Sinai, Egypt. Significant ontogenetic changes from juvenile to adult include: 1) increase in height of the ventral median septum; 2) change from hypothyridid to mesothyridid pedicle foramen; 3) change from a pyriform to a gibbous outline; 4) change from a weakly defined to a strongly defined pedicle sulcus; and 5) change from a relatively straight to a strongly arched lateral commissure. All ontogenetic stages, except for neanic, possessed a pedicle tube. Muscle scars (diductor) were observed for the first time in the genus on several pedicle valve interiors; none were noted on any brachial valve interiors. Juveniles lived epifaunally, attached to the substrate by a small but functional pedicle, while adults lived semi-infaunally with the umbos buried in the mud.

Analyses of shell shape variation in epifaunal and semi-infaunal myalinids from the LaSalle “cyclothem” attest to the extensive shape plasticity of some Late Pennsylvanian myalinids. Mean shell shapes differ significantly within and among species across three nearshore facies. Discriminant analyses of Fourier biometric data categorized by taxonomic, populational (habitat), life-mode, and “multi-species habitat assemblage”” discriminant groups reveal patterns of shape change and variation across an inferred environmental stress gradient in addition to taxonomic and life-mode shape differences. Fourier harmonic data are good indicators of shape differences between epifaunal and semi-infaunal life modes. Mean shapes of epifaunal species vary among habitats. Within-habitat shell shape convergence occurred between Myalina glossoidea and M. (Orthomyalina) slocomi. Interpopulational shape divergence occurred among all populations of M. (Orthomyalina) slocomi, M. glossoidea, and M. wyomingensis. Within-species variation among habitats produced significant mean shape differences among each of three “multi-species habitat assemblages.” Results indicate that a portion of the variation is of ecophenotypic origin.

Mean interspecific shape differences reflect internal functional organization and life modes. Intraspecific shape differences among epifaunal species could reflect physical and biotic habitat variables. Several harmonic amplitudes vary in concert with inferred environmental variation among habitats. Although biologic interpretation of harmonic data is problematic, parallel trends in fifth harmonic amplitudes of epifaunal species mirror inferred differences in water turbulence among habitats and could reflect shape variation related to byssal attachment.

Stress gradient trends in intraspecific shape variability cannot be collectively explained by either of the antithetical stability-diversity-variation hypotheses. Each species exhibits a different nonmonotonic trend. Maximal levels of intraspecific variation within each species occurred within different habitats. Within-species differences in levels of variation could result from genetic variation among populations as well as ecophenotypic influences. Comparative studies of ontogenetic shape change between valves of individuals, among individuals, and among populations are necessary to determine the relative influence of environmental variables on shape variation and evolutionary significance of phenotypic plasticity.

Collection of over a dozen specimens of Hyolithes aclis Hall from the Middle Devonian of New York indicates that this species belongs to a new genus, Hallotheca, to which the species Hyolithes halli (Hall) is also assigned. However, the generic assignments of the Silurian species Hyolithes cliftonensis Foerste and the Devonian species H. centennialis Barrett, H. ceratophilus Clarke, H. neapolis Clarke, and H. triliratus Hall are uncertain because of poor preservation of their type specimens. Use of these names should be confined to the types until better preserved topotypes become available. Finally, H. cooperi (Williams) consists of organisms of uncertain affinities, and the type of H. principalis Hall may be a fragment of Devonian sandstone rather than an organism.

Large palaeotrochid gastropods of the genera Floyda Webster (1905a) and Turbonopsis Grabau and Shimer (1909) occur in the late Frasnian Lime Creek Formation of Iowa. Floyda concentrica was designated as the type species of Floyda by earlier workers (Webster, 1905a; Knight, 1941), but is a junior synonym of F. gigantea (Hall and Whitfield, 1873). Three of five species and subspecies of Floyda described from the Lime Creek (Floyda concentrica, F. concentrica multisinuata, and F. gigantea depressa) are considered synonyms of the type species F. gigantea; the fifth species, F. gigantea hackberryensis, is here reassigned to the closely related genus Turbonopsis. Both F. gigantea and T. hackberryensis are redescribed using the original types and additional hypotype material from the collections of Charles Belanski.

Floyda, first known from late Givetian rocks of the Rhenish Slate Mountains in Germany, is widespread in the United States Midcontinent and western North America by early Late Devonian time. Turbonopsis was endemic to the Appohimchi Subregion of the Eastern Americas Realm prior to the Taghanic Onlap, and appears to have remained so until late Frasnian time when it migrated to western North America.

Eustatic sea-level highstands during the Middle and Late Devonian are thought to have breached barriers to migration, allowing both Floyda and Turbonopsis to disperse by prevailing oceanic currents from the United States Midcontinent into western North America during the late Frasnian. The expected oceanic current patterns of the Middle and Late Devonian paleogeographic reconstructions of Heckel and Witzke (1979, figs. 3, 5) adequately account for the known distribution and dispersal of Devonian palaeotrochid gastropods.

The Palaeotrochidae underwent extinction prior to the latest Frasnian. Floyda, Turbonopsis, and Westerna became extinct during the onset of the last eustatic deepening event prior to the close of the Frasnian. The extinction of the palaeotrochid gastropods as well as other invertebrate groups may have been the result of restriction or near elimination of shallow warm-water, well-oxygenated shelf habitats by the onlap of cold anoxic bottom waters prior to latest Frasnian time.

Specimens of a new species of the Permian waagenophyllid coral genus Waagenophyllum, W. klamathensis, have been recovered from limestone lenses near the top of the Upper Permian Dekkas Formation in the eastern Klamath Mountains, and similar specimens have been collected from an isolated limestone mass in the eastern Hayfork terrane of the southwestern Klamath Mountains, northern California. Another specimen of Waagenophyllum, which may represent another species, has been recovered from another limestone mass in the Hayfork terrane. These specimens of Waagenophyllum, a genus which otherwise is restricted to the Tethyan Province, provide the only tie between the Permian limestone masses of the eastern Hayfork terrane, which also contain typical Tethyan foraminifers, and the eastern Klamath Mountains terrane (McCloud belt), which contains many fossils with non-Tethyan affinities.

The pelecypod genera Slava and Rhombopteria are reported for the first time from Canada, where they occur in a limestone concretion within the Cape Phillips Formation, Cornwallis Island, Arctic Archipelago. These genera are characteristic of Silurian rocks in Bohemia, Czechoslovakia. Graptolites from the same concretion indicate the Monograptus ludensis Zone (uppermost Wenlockian); this age is substantiated by associated conodonts, trilobites, vertebrates, and pelecypods but with less precision. It is difficult to explain the occurrence of Slava and Rhombopteria in the middle of Laurentia on the basis of some map reconstructions of the Wenlockian world.

The Canadian material of Slava novaterra n. sp. and Rhombopteria cf. R. mira (Barrande) is described. Leptodesma (Leptodesma) sp. A and an indeterminate grammysiid pelecypod from the same concretion are illustrated. Information is provided to show that Newsomella Foerste, from Wenlockian–Ludlovian rocks of Illinois, Wisconsin, and Tennessee, is not a subgenus of Rhombopteria Jackson.

A Recent sinusoidal trail made by a biting midge (family Ceratopogonidae, genus ?Bezzia) moving on the surface of wet mud along the edge of a freshwater pond has been observed. The trail is similar to the trace fossil Cochlichnus Hitchcock, 1858. The wave length, wave amplitude, and overall form and shape of this modern trail compares favorably to Eocene wave-like trails attributed to nematodes. Consequently, a ceratopogonid larva is believed responsible for at least some of those fossil trails.

A newly discovered ammonoid, Mimagoniatites nearcticus n. sp., is described from upper Zlichovian–lower Dalejan (Lower Devonian) strata in the Canadian Arctic Archipelago. This species is distinguished primarily by its extremely narrow profile and high degree of whorl involution. It is the most gracile species so far known in the genus, and displays possible kinship to Parentites praecursor Bogoslovsky. This record constitutes the first definite occurrence of a Lower Devonian ammonoid from the Canadian Arctic Archipelago.

Burrows of the thalassinidean shrimp Callianassa californiensis and Upogebia pugettensis, which resemble the trace fossils Thalassinoides and Ophiomorpha, respectively, occur on the southern tidal flats at the western front of the Fraser Delta. Burrow densities for both shrimp species are highest at lower intertidal levels immediately inshore of an extensive bed of Zostera marina eelgrass, but the high-density shrimp populations are segregated: the highest densities of C. californiensis burrows (350–450 burrow openings/m2) occur in a strip of clean sandy sediments, whereas U. pugettensis burrows are most abundant (30–80 burrow openings/m2) in a patch of muddy sands and sandy muds. On the tidal flats of the Fraser Delta as a whole, however, textural properties of the sediment show no consistent correlation with the burrow density of either shrimp.

In the eelgrass bed, eelgrass root mats appear to markedly restrict the density of C. californiensis burrows. Towards the shore, the well-lined dwelling burrows of U. pugettensis occur no higher than mean sea level where maximum continuous exposure is ≤0.5 days. In contrast, C. californiensis, which has an unlined feeding burrow and a higher tolerance for anoxia, is present up to the margin of the local salt marsh which lies near the mean higher high water level where the flats can be exposed continuously up to 5 days.

In situ experiments indicate that C. californiensis extrudes 18 ± 9 ml of wet sediment/shrimp/ day onto the substrate surface, while U. pugettensis seldom forms a mound around its burrow entrance. Burial of filter-feeding postlarval U. pugettensis under the mounds produced by C. californiensis may increase postlarval mortality and reduce adult populations of U. pugettensis in areas of high C. californiensis burrow density.

The results of this study suggest that in distinguishing Ophiomorpha from Thalassinoides more emphasis should be placed on the presence of an extensive burrow lining in Ophiomorpha than on the presence of a knobby burrow exterior, because the former characteristic has a more profound bearing on burrow function, physiology of the occupant organism, and, consequently, burrow distribution.

Thirty localities in the Upper Paleozoic (Mississippian–Permian) of North America have yielded more than 1,000 cephalopod mandibles preserved as carbon films, pyrite/limonite internal molds, and as nuclei in phosphate, carbonate, and ironstone concretions. With occasional exceptions, cephalopod mandibles, as part of either the microfauna or macrofauna, are rare despite the fact that co-occurring cephalopods may be extremely abundant. Without exception, the mandibles recovered co-occur with ammonoids and very frequently with bactritoids. Localities containing only nautiloids, either coiled or orthoconic, have not yet yielded cephalopod mandibles. Also, nekroplanktic accumulations of cephalopods have not yielded mandibles. Except for Lagerstätten deposits (two occurrences), the cephalopod mandibles were always recovered from molluscan-dominated communities; these communities have been interpreted as being in relatively offshore, “deeper” water in normal marine salinities with relatively low to anoxic oxygen conditions.

Open-coiled euomphalacean gastropods have been identified for the first time in the Upper Cambrian Eminence Dolomite of Missouri. These gastropods have a triangular whorl profile and are conspecific with Hyolithes walcotti described from the Upper Cambrian of Nevada. That species is questionably reassigned to the gastropod genus Macluritella, hitherto known only from the Lower Ordovician of Colorado.

A detailed morphological study of over 2,500 Middle Ordovician (Black Riveran) lophospirid archaeogastropods from the lower half of the Platteville Formation (Pecatonica Member and Mifflin Submember of the McGregor Member), principally as it is exposed in southern Wisconsin, has permitted the definition of five species of Lophospira. Lophospira perangulata (Hall), L. milleri (Hall), L. serrulata (Salter), L. helicteres (Salter), and L. delicata (n. sp.) are preserved throughout a three-meter interval of fine-grained, heavily bioturbated carbonates, now dolomitized. Deposition took place on a broad, shallow tropical shelf, which was characterized by low rates of deposition and low physical energy. The sampled interval represents about 500,000 years. The benthic marine invertebrate fauna is well preserved, diverse, and characteristic of an environment of normal marine salinity.

Of the five Lophospira species, only one, L. perangulata, has been positively identified in older strata (late Whiterockian, eastern North America). The other four species were endemic to the interior seas, and apparently at least two of these, L. serrulata and L. helicteres, did not survive into post-Platteville (post-Black Riveran) environments. Changes in the proportions of lophospirid species from the Pecatonica into the Mifflin strata probably reflect subtle changes in the distribution of carbonate shelf habitats but no major alteration in the kinds of habitats available for colonization.

Pharkidonotus megalius n. sp. is described from the Desmoinesian of the Mud Springs Mountains, New Mexico. This unusually large bellerophontid reaches a length of at least 90 mm and is also characterized by a prominent high median ridge bearing a narrow selenizone and subdued collabral ornamentation on the whorl surface at all stages of growth. Its size and subdued ornamentation are quite different from that of the two previously known North American Pennsylvanian species of Pharkidonotus. Although steinkerns of comparable size have been reported from several localities in North America, the specimens discussed here are the first relatively well preserved shells of very large Pennsylvanian bellerophontids to be described.