Early Ordovician brachiopods Spanodonta floweri (Cooper) and Aporthophyla tianjingshanensis? Fu from peninsular Thailand and the Langkawi Islands, Malaysia, and described and offer important confirmatory evidence for the Ordovician juxtaposition of the Shan-Thai terrane, the North China terrane, and Western Australia.

A megafossil flora, composed of 12 form taxa, has been collected from the Upper Mississippian–Lower Pennsylvanian Surprise Canyon Formation in the Grand Canyon, Arizona. It is the first known flora of this age to be recorded in Arizona, and includes Lepidodendron aculeatum Sternberg, L. mannabachense Presl, L. volkmannianum Sternberg, Lepidostrobus sp. cf. L. ornatus Brongniart, Lepidostrobophyllum sp., Knorria sp., Cyperites sp., Stigmaria ficoides (Sternberg), Calamites (Mesocalamites) cistiiformis Stur, Calamites sp., Pecopteris cf. P. aspera, and Wardia sp. (seed). The 22 species of palynomorphs previously reported from this formation suggest that the local flora was more diverse than the paucity of plant megafossil specimens indicates.

Melanosclerites are rod-shaped, pseudochitinous microfossils of problematic affinity. They have not been widely studied. The first North American discovery of melanosclerites is here reported; Melanostylus coronifer and Melanosteus acutus (the latter with two subspecies), of Devonian (Late Siegenian) age, were discovered in the Indian Cove Formation of the Upper Gaspé Limestones from the Gaspé Peninsula, Quebec, Canada.

These melanosclerites bear a strong resemblance to the modern cubomedusa polyp Carybdea alata and the planula stages of the hydrozoan Pennaria tiarella. They are interpreted as being the embryonic planula and early polyp stages of scyphozoans, cubozoans, and hydrozoans.

Consequently, Semenola semen Schallreuter, 1981, is considered an early growth stage of M. acutus anceps and thus a junior synonym; similarly, Eichbaumia incus is a junior synonym of Melanostylus coronifer; while, on the basis of their three-fold symmetry, Orthopelta? femuralis Eller, 1945, and Menola os Schallreuter, 1981, are treated as junior synonyms of Melanofurca neptuni Eisenack, 1963. Melanosclerites could represent the planula and polyp stages of any of the three classes of Cnidaria; therefore, the order Melanoscleritoitidea Eisenack, 1963, and the family Melanoscleritoitidae are here rejected because the supposed family crosses the boundaries of classes. The new subspecific combinations Melanosteus acutus acutus, M. acutus filiformis, and M. acutus anceps are proposed, their diagnoses being emended; the diagnosis of Melanostylus coronifer is also emended.

Melanosclerites appear to be strongly facies controlled and thus may have potential for paleoenvironmental and paleogeographical reconstructions.

The fissurellid, haliotid, and scissurellid gastropods described herein are representatives of a diverse, but poorly documented, molluscan assemblage from the Upper Cretaceous carbonate-platform deposits of the Caribbean Faunal Province. Among the Fissurellidae, the Emarginulinae are represented by Emarginula pojetai n. sp., E. marchmontensis n. sp., E. sp., Puncturella (Alatrix) leesi n. sp., and P. (A.) sp.; the Diodorinae by Diodora decussata n. sp., Diodora hazeli n. sp., Diodora? pedinostoma n. sp., and D. sp.; the Fissurellinae by Fissurella kollmanni n. sp. Haliotis antillesensis n. sp. is only the second verifiable member of the family Haliotidae to be described from the Cretaceous and Scissurella marchmontensis n. sp. represents the first record of the Scissurellidae in that period.

A new molluscan genus, Voskopiella, from the Lower Devonian of Bohemia is described and assigned to the Onychochiloidea. The type and only known species is Voskopiella barborae n. sp. from the Nowakia elegans Zone (uppermost Zlichovian, =Emsian) of the Suchomasty Limestone. Also discussed are its ontogeny, variability, and pathological development of ornamentation, as well as the mode of life, in order to resolve the problem as to whether onychochiloideans are torted gastropods or untorted paragastropods. A foliage supported mode of life or life in close association on or within algal mats is suggested for Voskopiella barborae n. gen. and sp.

The Society of Sedimentary Geology (SEPM) joins with the Department of Geosciences and Keller Conference Center, Penn State University, in hosting the Society's 1993 Theme Meeting on the biotic, sedimentary, and geochemical indicators of past global change. The goal of this meeting is to bring together researchers studying the stratigraphic record with researchers using physically based models. Tentative Symposia topics include:

Clinal variation is systematic, morphologic variation within a species along a geographic or ecologic gradient. While common among today's biotas, it has rarely been well documented in the fossil record. It is, however, clearly displayed among the large populations of the Trentonian brachiopod genus Sowerbyella. In general, shallow agitated waters were populated by specimens with flat or round pedicle valve exteriors and ornately sculptured brachial valve interiors. Deeper, quieter facies were populated by forms with medial folds on pedicle valve exteriors and plain brachial valve interiors. This clinal variation was apparently the product of heterochrony with either the shallow-water forms having been peramorphic or the deeper water forms having been paedomorphic.

The distributions of the Sowerbyella clines are directly related to the facies developed within approximately eight million years of continuously deposited strata of the Trenton Limestone. Evolution of the Trentonian species of Sowerbyella appears to have been phyletic and locally adaptive. New clinal variants evolved by orthoselection during episodes when new environments were becoming available for occupation. The lower Trentonian transgression and the middle Trentonian shallowing were the major examples. Some clinal variants were eliminated when they failed to pass through facies bottlenecks in the lower and upper Trentonian. Thus, the history of the Sowerbyella lineage of the Trenton Group is the product of the facies-controlled production and selection of clinal variants. Clinal variation appears to be a central factor of phyletic evolution.

Sowerbyella kayi n. sp. is described.

Forty-three species of 25 genera are described in a collection of 170 large, massive reef corals from the upper Eocene Gatuncillo Formation near Lago Alahuela in central Panama. Comparisons with type material for other Eocene Caribbean reef corals suggest that 27 of these species are new. Twenty-four of these species are named herein. Like other Eocene Caribbean reef-coral faunas, the fauna is rich in Astrocoenia, Actinacis, and Astreopora; however, unlike other faunas, plocoid and meandroid members of the family Faviidae (e.g., Montastraea, Agathiphyllia, Goniastrea, and Colpophyllia) are abundant. Also present are the oldest known representatives of the genera Meandrina, Coscinaraea, Alveopora, Heliopora, and Pocillopora, as well as the only recorded occurrences of Coscinaraea and Cyathoseris from the Caribbean. Comparisons with Oligocene and Recent Caribbean reef-coral faunas suggest that the generic composition of Cenozoic Caribbean reefs became established during the Eocene. With exception of the family Mussidae, much of the post-Oligocene history of the Caribbean is one of extinction at the generic level (19 of the 28 Eocene genera became extinct) and proliferation of species within the surviving genera.

Two orthothecid genera, Bolitheca n. gen. (type species Orthotheca steinmanni Knod, 1908) and Neobactrotheca n. gen. (type species Neobactrotheca pharetra n. sp.) are described from Bolivian rocks of Emsian and Eifelian age. Two incomplete and poorly preserved hyolithids are also described, one tentatively assigned to the family Pauxillitidae. Because so few specimens are known, it is not possible to compare Bolivian Devonian hyoliths with faunas from other regions, which are also poorly known.

New collections of Caradoc brachiopods from the lower half of the Fombuena Formation in the Iberian Chains (northeastern Spain) have yielded rich fossil associations that, in spite of the endemism of most of their species, permit detailed correlations with other sequences in southwestern Europe, Bohemia, and the British Isles. The oldest association studied occurs at the top of the basal oolitic ironstone of the Fombuena Formation, where 10 brachiopod species have been recorded; the youngest association occurs in sandstones in the middle part of the unit, having yielded seven brachiopod species. Herein, 11 forms are described including four new species (Gelidorthis carlsi, Saukrodictya tormoensis, Reuschella herreraensis, and Rostricellula marciali) and one new subspecies (Aegiromena aquila intermedia). The stratigraphic setting of the oolitic ironstone and its brachiopods suggest a correlation with similar beds that crop out at various localities in the Iberian Peninsula and northwestern France, as well as with the Zdice-Nucice Iron Ore, placed at the base of the Vinice Formation in Bohemia. The regressive–transgressive cycle, whose point of maximum shoaling coincides with the deposition of the apparently widespread ferruginous bed, is restricted to the Mediterranean Province and may have been caused by regional epeirogenic movements. The stratigraphic gap marked by the ironstone had been assessed at several localities in Iberia and Armorica; it ranges from late Costonian to Soudleyan, an age not in disagreement with the occurrence of a new species of Reuschella immediately above the ironstone of the Iberian Chains, since Reuschella is not known before the Soudleyan. Dalmanella unguis unguis, which has been recorded in the youngest assemblage and which in Wales is restricted to the Marshbrookian, is another important guide form in the problematic correlation between the Mediterranean Caradoc and the British type sequence.

An assemblage of well-preserved octocoral holdfasts and sclerites has been collected from the Red Bluff Formation at the Chickasawhay River, Wayne County, Mississippi. Seven families were identified, utilizing a collection of approximately 1,000 sclerites. Families represented are Telestidae, Nephtheidae, Anthothelidae, Paramuriceidae, Plexauridae, Virgulariidae, and Gorgoniidae. These families, with exception of the Gorgoniidae, are here reported for the first time as fossils from the Gulf Coast region. The collection represents one of the most diverse fossil octocoral assemblages known from a single location.

The type material of Ilionia prisca (Hisinger) is redescribed. This species shows several basic morphological characteristics typical of Recent Lucinacea, including an anteriorly expanded shell with conspicuous diagonal sulci, a hypertrophied anterior adductor muscle scar, and a nonsinuate pallial line. It is believed to have been a suspension feeder provided with a posterior exhalant siphon and capable of forming an anterior inhalant mucus tube in the sediment. Ilionia prisca lived in a habitat unfavorable for most other bivalves, deeply buried in a soft, oxygen-poor and sulphur-rich mud, in which it oriented itself obliquely against the direction of water movement. Probably it lived in symbiosis with chemoautotrophic bacteria. It is suggested that Ilionia prisca is the oldest known deep-burrowing suspension-feeding bivalve.

Evaluation of previously undescribed collections of Late Triassic Gryphaea from the North American Cordillera increases the temporal range and geographic distribution of the genus. Gryphaea (Gryphaea) arcuataeformis Kiparisova, G. cf. G. (Gryphaea) keilhaui Böhm, and a new species, G. (Gryphaea) nevadensis, occur in lower Carnian to upper Norian strata from Alaska, British Columbia, Oregon, and Nevada. The distribution is mostly primary with respect to the Upper Triassic North American Craton, and requires long-distance larval dispersal along the latitude of far-eastern Panthalassa. Unlike most modern oysters, the distribution of these Triassic gryphaeids may have been restricted to cool and deeper water environments.

An early Carnian age of Gryphaea (Gryphaea) arcuataeformis places this species as the oldest known Gryphaea. When combined with late Carnian and Norian occurrences from the North and South American Cordillera, these data indicate that a low-latitude origin for the genus cannot be overlooked. Gryphaeids survived the end-Triassic extinction event presumably by living in refugia.

Two specimens of the Cretaceous genus Pictetia Uhlig, 1883, have been found in the Cottonwood District, northern California, the first record of this genus in North America. The larger specimen is a septate whorl fragment from the Brewericeras hulenense zone that is associated with Douvilleiceras mammillatum. It is identified as Pictetia sp. The smaller specimen is a septate fragment of one and a half whorls from the Oxytropidoceras packardi zone associated with Cleoniceras. It is identified with the type species, Pictetia astieriana Orbigny, 1842, previously recorded from Europe. A review of the genus Pictetia suggests that species assigned to the genus have an open coil with a rounded dorsum. The occurrences of these Tethyan elements in the Albian fauna of the Cottonwood District suggest easy communication for many Cretaceous taxa between northern California and the Tethyan realm of Europe, the Caucasus, and Madagascar.

Three new species of freshwater gastropods are described from the lower Eocene Adjuntas Formation. Five more species are reported from the same fauna. This is the first report of Tertiary freshwater Mollusca of the Campanian–lower Eocene Difunta Group. The three new species (Hemisinus (Longiverena) reticulosus, Hemisinus (Longiverena) adjuntaensis, and Melanatria ypresiana) belong to the family Thiaridae, which today is a worldwide distributed group of freshwater gastropods of medical importance. Paleoenvironmental interpretation for red, green, and yellow beds of Adjuntas Formation suggests delta-plain deposits. Gastropods here described lived in swamps and marshes of this portion of the ancestral Gulf of Mexico.

The naticid gastropod predator–prey system has been cited as a possible example of coevolution. Previous work indicated that Miocene bivalves from the Chesapeake Group responded to naticid drilling with a predation-avoidance strategy of gradual thickness increase over evolutionary time. The present study examined whether the predators, Euspira heros (Say) and Neverita duplicata (Say), coevolved by increasing their efficiency in response to prey adaptation.

Neither predator showed significant trends in most characters thought to affect predator efficiency, including measures of globosity and aperture size relative to shell height. Stasis occurred for all such characters except Euspira aperture height, which showed a statistically significant decrease of 9 percent through the section. Morphologic trends occurred in two additional characters, shell thickness relative to height, and shell height. Euspira increased in thickness by 63 percent through the section; Neverita decreased in thickness by 37 percent (through slightly less section) and simultaneously increased mean height by 60 percent.

The size increase exhibited by Neverita could be interpreted as a coevolutionary response to increased prey defenses. Naticids are subject to predation by other naticids, however; the trends in size and thickness may be viewed instead as an evolutionary strategy to escape naticid predation, including cannibalism. Although the possibility of coevolution is difficult to eliminate, Chesapeake Group naticids appear to have evolve more in response to their own predators than to evolution of their prey.

A large, diverse, and well-preserved fauna of nonmarine mollusks has been recovered from the late Oligocene to early Miocene (Arikareean) fluviatile and lacustrine sediments that accumulated in four intermontane structural basins of western Montana. The Pupillidae are represented by 10 species, with nine new species and one new subgenus among three extant genera. The Gastrocopta are very diverse, with one new subgenus Ameralbinula represented by three new species, G. obesa, G. russelli, and G. oviforma, while three new species, G. tavennerensis, G. leonardi, and G. conica, are referred to the extant subgenus Vertigopsis Sterki, 1893. Gastrocopta miniscula cannot be referred to a subgenus with certainty. The remaining new species, Vertigo whitei and Pupoides montana, are referred confidently to extant subgenera. Vertigo arenula (White, 1876) is the only previously described species and its description is emended based on new material. The mammalian biostratigraphy of the Cabbage Patch beds is presented.