Recent sampling for larger foraminifers in the so-called Polylepidina gardnerae horizon in the middle Eocene Lisbon Formation of the Little Stave Creek section, southwest Alabama, did not produce any examples of the lepidocyclinid foraminifer Polylepidina gardnerae Cole, but several specimens of the stratigraphically younger species, Lepidocyclina ariana Cole and Ponton, were recovered. Although the P. gardnerae horizon is named on nearly all figures of this important Gulf Coast section published since 1944, preliminary research has also failed to turn up a published basis for the identification of P. gardnerae at this locality. As L. ariana and P. gardnerae are not normally found together, it is the writer's opinion that true P. gardnerae probably has not been collected from any part of the Lisbon Formation at Little Stave Creek. If it does occur, it should be found at a lower horizon than that indicated in the literature.

Halkieriids are known largely from isolated sclerites, although it is understood that originally they formed the scleritomes of slug-like animals in Lower Cambrian benthic environments. The Yurtus Formation (?Tommotian–Atdabanian equivalent) of the Aksu-Wushi area, west Xinjiang, China, has yielded abundant sclerites. These are secondarily phosphatized, but show considerable detail. The sclerites can be divided into three classes: cultrates, long palmates, and short palmates; definite siculates have not been recognized. In some samples elongate to semicircular shells co-occur with the sclerites; these may derive from the same halkieriid scleritome. The external surface of the shells may bear a subdued ornamentation. The concave interior, however, is remarkable on account of a unique structure consisting of a group of nodular-like units. These may be arranged in a low cone or dispersed in a small circle. In addition to the sclerites of halkieriids and their possibly associated shells, rarer material is attributable to the related group of siphogonuchitids.

Most of the specimens of Myoscolex ateles Glaessner, 1979, the most abundant soft-bodied taxon in the Big Gully fauna from the Lower Cambrian Emu Bay Shale of South Australia, preserve only the phosphatized trunk muscles, in striking contrast to the organic residues that characterize other Burgess-Shale-type biotas. This is the oldest phosphatized muscle tissue and the first thus far reported from the Cambrian. The extent of phosphatization implies a source in addition to the animal itself, and this is reflected in high levels of phosphate in the Big Gully sequence compared to other shales. The apparent anomaly posed by the extensive preservation of labile muscle tissue as opposed to the more decay resistant cuticle is explained by the role of bacterial processes in the preservation of soft tissues. New specimens of Myoscolex reveal a variable number of trunk somites with possible tergites, and flap-like appendages. There is evidence for at least three eyes on the head, and a proboscis may have been present. An annelid affinity is rejected and Myoscolex is reinterpreted as an Opabinia-like animal with possible affinities with the arachnomorph arthropods.

Cardiarina cordata Cooper, 1956, has previously been placed in the Rhynchonellacea. Specimens present in the Dickerson Shale (Pennsylvanian, Desmoinesian) in north-central Texas have a terebratulid centronelloidiform loop, and although there are no punctae preserved, are questionably assigned to C. cordata and placed in the Terebratulacea.

Shell-encrusting assemblages have uniquely high ecological fidelity among paleocommunities because adjacent epibionts coexisted in ecological time, and the abundances and spatial relationships of the various members are accurately preserved. This study presents a quantitative reconstruction of communities on brachiopod shells (Composita and alate spirifers) from the Carboniferous of North America. Thirty-one epibiont communities, comprised of a total of 1180 encrusted brachiopods, are analyzed in terms of epibiont abundance (e.g., percent areal cover), ecological diversity (e.g., Shannon-Wiener Index), and the role of larval recruitment and spatial competition in structuring the communities.

Mississippian epibiont communities contain from seven to 14 encrusting taxa that occupy up to 25 percent of host shell surfaces. These communities are spatially dominated by trepostome bryozoans, but also include common lower Paleozoic epibionts, such as encrusting ctenostome bryozoans, hederellids, cornulitids, and edrioasteroids. Pennsylvanian epibiont communities contain between eight and 16 epizoan taxa that occupy up to 34 percent of shell surfaces. They are dominated by fistuliporoid or trepostome bryozoans and increasing proportions of erect bryozoans (e.g., fenestellids), encrusting foraminiferans, and articulate brachiopods.

Carboniferous epibionts, like their modern counterparts, exist in loosely organized ecological communities that vary widely in abundance and composition in space and geological time. There is little evidence for tight controls on community structure. Much of the variation is attributed to vagaries in the magnitude and selective nature of larval recruitment. Evidence of competition between community members is rare, except where a high percentage of the shell surface is covered. In these cases, sheetlike bryozoans are usually most abundant. Solitary epibionts are surprisingly successful competitors in one-on-one encounters, but apparently lose areal cover to longer-lived colonial encrusters during ecological succession.

This paper describes Byzantia obliqua, new genus and species. Byzantia is a small, distinctively ornamented, gastropod genus from the middle Permian (Leonardian-Guadalupian) of West Texas. This provides further evidence of the diversity of the Neritacea in the middle Permian and of the diverse endemic fauna of west Texas.

The microstructure of the non-window portions of the shell of Corculum cardissa resembles other Fraginae, with predominantly fibrous prismatic outer, branching crossed lamellar middle, and complex crossed lamellar inner layers. Both the anterior and posterior windows in its shell reflect reduced pigmentation and incursion of the outer shell layer, but the posterior windows involve deeper incursion plus reduction of the outer and middle sublayers of the outer shell layer and microstructural modification of the middle shell layer to enhance light transmission. The planoconvex shape of the posterior windows has more likely evolved to direct and focus light toward the deeper, zooxanthellae-rich gills and anterior mantle, than to merely disperse light.

New collections from the Marshalltown Formation and basal Mount Laurel Sand along the Chesapeake and Delaware Canal in Delaware clarify the ammonite dating of the interval. The Marshalltown Formation yields Pachydiscus (Pachydiscus) sp., Menuites portlocki (Sharpe, 1855) complexus (Hall and Meek, 1856), a subspecies restricted to the Baculites gregoryensis and Baculites scotti zones in the Western Interior of the United States, and Didymoceras binodosum (Kennedy and Cobban, 1993a) known only from the B. scotti zone of the Western Interior and correlatives in Arkansas and Texas. The basal part of the Mount Laurel Sand contains a complex assemblage preserved as phosphatic molds: Nostoceras (Nostoceras) monotuberculatum Kennedy and Cobban, 1993a, Nostoceras (N.) sp., Didymoceras platycostatum (Kennedy and Cobban, 1993b), D. stevensoni (Whitfield, 1877) (previously thought to be from the Marshalltown) and Exiteloceras jenneyi (Whitfield, 1877). The last two are index species of their eponymous zones in the Western Interior. This sequence is compatible with ammonites from the Wenonah Formation, which lies between the Marshalltown and Mount Laurel to the north and contains ammonites indicative of the Baculites scotti zone, and the fauna from higher in the Mount Laurel Sand, which includes elements of the Didymoceras cheyennense and Baculites compressus zones of the Western Interior sequence.

Agnostoid trilobites from the Carlos Rusconi collections in the Museum of Natural Sciences of Mendoza, Argentina, are revised. The agnostoids were collected in the southern Precordillera of Mendoza Province, western Argentina. Revised taxa include Agnostus microcephalus (Rusconi), Lotagnostus (Lotagnostus) peladensis? (Rusconi), Lotagnostus (Lotagnostus) lasherensis (Rusconi), Homagnostus pehuenchensis Rusconi, Kormagnostus seclusus (Walcott), Kormagnostus? beltensis (Lochman in Lochman and Duncan), Hypagnostus parvifrons (Linnarsson), Ptychagnostus cuyanus (Rusconi), Ptychagnostus aculeatus (Angelin), Lejopyge laevigata (Dalman), Tomagnostella exsculpta (Angelin), Diplagnostus planicauda (Angelin), Oedorhachis typicalis Resser, Clavagnostus calensis Rusconi and Clavagnostus repandus (Westergård in Holm and Westergård). Some taxa of uncertain affinities are recognized and new specimens assignated to Lotagnostus and Pseudagnostinae are illustrated. Hypagnostus parvifrons, L. laevigata and C. repandus are reported for the first time in South America. Global correlation with previously described agnostoid faunas indicates that the outcrops range from middle Middle Cambrian to latest Late Cambrian in age.

Trilobites assigned to 29 genera and 39 species are reported from the Deadwood Formation in the Black Hills of South Dakota. Two new species, Prosaukia lochmani and Arcifimbria pahasapaensis, are described. Brachiopods are reported from the Taenicephalus Zone.

A biostratigraphic zonation is established for the upper part of the Deadwood Formation. The Taenicephalus Zone in the lower part of the study interval is succeeded upsection by the Ellipsocephaloides Zone, both of which are assigned to the Franconian Stage. These two zones are overlain in turn by the Illaenurus and Saukia Zones of the Trempealeauan Stage. These zones are used to correlate this part of the Deadwood with coeval strata in Montana and Wyoming, central Texas, Oklahoma, and Alberta, Canada. The lowstand of sea level that occurred in the Great Basin at the time of the deposition of the Saukiella junia Subzone of the Saukia Zone probably extended eastward into the Black Hills, resulting in the absence of this fauna in the Black Hills.

Rare specimens of the Late Cambrian primitive libristomate trilobite “Cedaria” woosteri from the Eau Claire Formation of north-central Wisconsin preserve an unusual and new ocular suture, and the impressions of lens facets. The suture is circumocular, but loops abaxially onto the ocular platform. The portion of the ocular platform that is enclosed by this suture and is fused with the visual surface is here termed the “ocular plate”. The size and arrangement of the lens facets show that “C.” woosteri possessed a holochroal eye, typical of that known in other Cambrian libristomate trilobites. This nearshore assemblage, while low in diversity, contains a disparate array of trilobite morphotypes.

A growth series is described for a new species of Ceratocara Ramsköld, 1991, C. argentina, from the Upper Ordovician (Caradoc) part of the Las Aguaditas Formation, near Jáchal in San Juan Province, Argentine Precordillera. Another new species of Ceratocara, C. shawi, is described from the Middle Ordovician (lower Chazy) Crown Point Formation of New York. A phylogenetic analysis is presented for these species, other well-known Ordovician species of Ceratocara, and some Ordovician species of Ceratocephala, with Ceratocephalina tridens Whittington, 1956, as outgroup. The analysis presented supports the monophyly of both Ceratocara and Ceratocephala Warder, 1838, their divergence having occurred by the middle Arenig. The ontogenies of the Ceratocara species from Argentina and New York, complete from protaspid to holaspid growth stages, are some of the best preserved odontopleurid ontogenies described to date. Material of Ceratocephala triacantheis Whittington and Evitt, 1954, from the Crown Point Formation of the Chazy Group of New York, is discriminated from that of Ceratocara shawi.

The description of a new species of retroplumid crab, Costacopluma salamanca from the Danian Salamanca Formation, southern Argentina, represents the eighth species referred to that genus and extends the geographic range of the taxon into Patagonia. Cladistic analysis of the genus suggests that three groups of species can be identified based upon their geographic position; Afro-Asian, North American, and South American.

Systematic restudy of Lower Mississippian disparid crinoids from the midcontinental United States results in the recognition of nine valid species and one left in open nomenclature. Although disparid crinoids are not diverse, they may be locally abundant and be the dominant crinoids in certain settings. The following species are considered valid: Catillocrinus tennesseeae Shumard, Catillocrinus wachsmuthi (Meek and Worthen), Eucatillocrinus bradleyi (Meek and Worthen), Halysiocrinus bradleyi (Meek and Worthen), Halysiocrinus cumberlandensis new species, Halysiocrinus springeri Brower, Halysiocrinus tunicatus (Hall), Synbathocrinus blairi Miller, and Synbathocrinus swallovi Hall. Several species are placed into synonymy. Catillocrinus shumardi Springer and C. turbinatus are considered junior synonyms of C. tennesseeae. Halysiocrinus granuliferus and H. perplexus are regarded as junior synonyms of H. tunicatus. Synbathocrinus angularis Miller and Gurley, S. granulatus (Wood), S. granuliferus Wetherby, S. robustus Shumard, and S. troosti (Wood) are deemed junior synonyms of S. swallovi. The youngest (Meramecian) North American calceocrinids, Halysiocrinus sp., are reported, herein, from the Harrodsburg and Salem Limestones of Indiana.

Purgatorius titusi, represented by 51 teeth and jaw fragments, is described from the lower Paleocene Bear Formation of the Crazy Mountains Basin in south-central Montana. Several synapomorphies, including a weak postprotocingulum and mesial inflection of molar trigonids, are indicative of the taxon's “plesiadapiform” affinities. Other features, such as wider stylar shelf and a less squared lingual outline on upper molars, are more primitive than those of Purgatorius unio, heretofore the earliest occurring species of well-represented primatomorphs.

While preparing the part of the Treatise on Invertebrate Paleontology dealing with Greenfieldia, Alvarez had problems with the absence of information regarding its jugum. GRABAU (1910, in Grabau and Sherzer) described the smooth, subequally biconvex, small shell Greenfieldia whitfieldi, the type species of his Greenfieldia, from the Late Silurian Greenfield Dolomite of northern Ohio. Grabau (1910, p. 149) remarked that the brachidium was unknown, with only the presence of laterally directed spiralia (Grabau, Pl. XXX, fig. 9) being indicated but not discussed in the text. Grabau (1910) considered a questionable assignment of Greenfieldia to the meristelloid Hindella. Boucot et al. (1965, p. H662), Berry and Boucot (1970, p. 155) and Berdan (1972, p. 16) all illustrated the difficulty in discriminating between the Late Silurian Protathyris, whose jugum is known and athyroid in type, and Greenfieldia with its unknown jugum. Jones (1978, p. 10) further emphasized the difficulty in discriminating between Protathyris and Greenfieldia owing to ignorance of the latter's jugum. Modzalevskaya (1979, fig. 7) described a jugum from a form assigned to Greenfieldia. The complex form of the jugum she illustrated, featuring a number of recurving branches, is entirely unlike that of Greenfieldia although relatively similar to that of Protathyris.

In 1988, the presence of an Early Pennsylvanian ammonoid assemblage within the basal meter of the Callville Formation (Pennsylvanian-Permian), eastern Clark County, Nevada, was brought to the attention of the author by Stephen M. Rowland, University of Nevada-Las Vegas. The ammonoids occur in the Frenchman Mountain section described by Rowland (1987) for the Geological Society of America's Decade of North American Geology (DNAG) field trip compendium. The mid-Carboniferous section at this locality (Figure 1) was discussed in two other field trip guides as well (Langenheim and Webster, 1979; Webster et al., 1984). No ammonoids have been reported previously from this locality. Although this is the first record of Cancelloceras from the Great Basin region, the assemblage also provides a narrowly constrained age for the basal part of the Callville Formation at Frenchman Mountain, which in turn, dates the initiation of carbonate deposition following a major mid-Carboniferous hiatus in the southern Great Basin.

Davydov et al. (1995) recently proposed the Aidaralash Creek section in northern Kazakhstan (Figures 2 and 3) as the Global Stratotype Section and Point (GSSP) for the base of the Permian System. The proposed boundary is the level in an evolutionary sequence where Streptognathodus wabaunsensis Gunnell gives rise to a descendent with an isolated node field on the inside of the upper platform surface. This morphotype constitutes a new and distinct species for which we propose the name Streptognathodus isolatus new species.