Two new species of the genus Nephasoma, phylum Sipuncula, are described from subtropical waters of the western Atlantic. Nephasoma (Nephasoma) columbaris is described from the central east coast of Florida where it is found along the edge of the continental shelf at depths of 61 to 104 m associated with the rubble from the reefs of the deep water coral Oculina varicosa. A second species, Nephasoma (Nephasoma) ditadii, is described from Brazilian waters in sand habitats at 150 m on the continental shelf off the coast of the state of São Paulo. Morphology of the two species is compared with allied species in the genus and the phylum. Usage in the taxonomic literature of the diagnostic characters “shield” and “pseudoshield” is reviewed and evaluated.

Three deep-sea species of Dorvilleidae are studied. Ophryotrocha fabriae, new species, collected at the Lucky Strike hydrothermal vent field (1620–1730 m depth, Mid-Atlantic Ridge), is the first dorvilleid described from Atlantic deep-sea vents. It resembles O. maciolekae Hilbig & Blake, 1991, another Atlantic deep-sea species but differs in prostomial and pygidial appendages, chaetae, and maxillae. The second dorvilleid species, collected at the Haakon Mosby Mud Volcano (1258 m, SW Barents sea slope, off Norway), differs only slightly from O. spatula Fournier & Conlan, 1994 from Canadian Arctic ice scours and is, therefore, reported as O. cf. spatula, being the first Ophryotrocha reported from a cold seep site. The third species, sorted from the Menez Gwen hydrothermal vent field samples (840–865 m, Mid-Atlantic Ridge), is reported as Ophryotrocha sp., as the material was inadequate for full identification.

Palpiphitime lipovskyae, new species, is described on the basis of specimens collected near an Atlantic salmon farm in Hecate Strait, British Columbia, Canada. The new species differs from P. lobifera (Oug, 1978), the only other described species in the genus, by having lamella-like dorsal and digitate ventral lateral lobes, its parapodia lacking ventral chaetal lobes, mandibles with fewer teeth, and P-forceps having serrated ridges with alternating large and small teeth. The definition of Palpiphitime Orensanz, 1990 is expanded to include the characteristic jaws.

Twelve new species from three genera of Gnathiidae are described: Caecognathia rhektos, Elaphognathia aldabrae, E. gladia, E. ramosa, Gnathia antonbruunae, G. eumeces, G. glauca, G. luxata, G. serrula, G. somalia, G. stoddarti, and G. zanzibarensis. Most are from the western Indian Ocean, with one from Thailand. Gnathia nkulu Smit & Van As, 2000, is newly recorded from Madagascar. Keys to the six species of Elaphognathia and 20 species of Gnathia from the Indian Ocean are presented.

We describe Alvinocaris komaii, new species, from hydrothermal fields at the Eastern Lau Spreading Center (ELSC). Adults of this species are distinguished in the field from other alvinocaridids at the ELSC by their larger size and orange-white carapace. Additionally, they appear to preferentially inhabit mussel beds composed of Bathymodiolus brevior. Alvinocaris komaii differs from all known species in the genus by a distinctive deep notch mesially on the telson and accessory spinules on the dactyli of the third to fifth pereopods arranged in 2 rows. A suite of morphological characters separates A. komaii from other alvinocaridids. We analyze the degree of morphological variation in A. komaii and discuss affinities of the Pacific species of Alvinocaris. Molecular data from the mitochondrial COI gene is used to compliment this description, and a key to the species of the family Alvinocarididae is included with locality information.

Pinnixa arenicola is redescribed and illustrated on the basis of new collections and reexamined type material. Its occurrence in the burrows of Upogebia vasquezi Ngoc-Ho is reported, along with range extensions that include Florida, Puerto Rico, Aruba, and the Cayman Islands. New collections represent the first reports of P. arenicola since original discoveries in Curaçao and suggest a potentially wide distribution of the species in the tropical western Atlantic. Following publication of the unillustrated original description for the holotype male, females were also noted to occur in Curaçao, but illustrations with limited detail were provided by Rathbun for only the male holotype specimen. Prior to our work, no illustrations have depicted female morphology, unique male gonopods, or some pereopod features of potential value in defining phylogenetic relationships.

A new species of pseudothelphusid crab, Fredius ykaa, from the Rio Marau drainage, in the middle Amazon basin, state of Amazonas, Brazil, is described and illustrated. The new species is characterized by a first gonopod with a straight border between the cephalic spine and the apex, as well as by a highly reduced mesial lobe relative to the size of the cephalic spine. The new species is compared with four other species of the genus Fredius Pretzmann, 1967, occurring in the Brazilian Amazon region and its geographical distribution is discussed.

A new genus, Sinotympana, and a new species, Sinotympana incomparabilis, are described from southern China. This genus is allied to the genus Haphsa Distant, 1905 but is distinguished by its much larger and wider body, largely black body coloration, short and wide opercula, longer abdomen, and uncal lobes that are fused together at the base.

Two new genera and species of well-preserved fossil holothurians are described from the Lower Cretaceous (Albian) of Tepexi de Rodriguez, Puebla, central Mexico. Parapsolus tlayuensis is a psolid, and Paleopentacta alencasterae is a cucumariid. Paleopentacta alencasterae is the first complete holothurian fossil known to have two types of body wall ossicles preserved. The presence of the families Psolidae and Cucumariidae suggests that the local habitat was a hard substrate. The two holothurian species described here are interpreted as shallow water-suspension feeding species.

Study of the type series and much new fossil material of the Cuban teratorn, Teratornis olsoni Arredondo & Arredondo, shows that this species possessed unique characters within the family Teratornithidae, including a shorter and more flattened humerus and femur, and a tarsometatarsus with a long trochlea II. The differences are so great as to merit a new genus, Oscaravis, for the species. Some osteological characters of Oscaravis suggest that it was less derived than Teratornis and possibly more similar to Argentavis. As the only insular member of the Teratornithidae, Oscaravis shows that teratorns were capable of overwater dispersal, so that the expansion of the family into North America from the south need not have been dependent on the presence of a land bridge.

While encamped for the winter of 1819–1820 at Engineer Cantonment along the Missouri River in present-day eastern Nebraska, members of Major Stephen Harriman Long's Expedition to the Rocky Mountains collected a number of animals that were previously unknown. Among the mammals were two soricids that were subsequently described by Thomas Say as Sorex brevicaudus (Northern Short-tailed Shrew, Blarina brevicauda) and Sorex parvus (Least Shrew, Cryptotis parvus). The holotypes of these species were deposited and placed on public exhibit in the Philadelphia Museum, the predominant North American systematic collection of the early nineteenth century. Like most private museums of that era, the Philadelphia Museum eventually went out of business, and its collections were dispersed and, for the most part, lost. Fortunately, Titian R. Peale made a detailed field sketch of the two specimens soon after their capture and subsequently executed a watercolor based on that sketch. In addition, an engraving of the holotypes was published in the decade following the discovery of the two species. Illustrations of holotypes are taxonomically useful when they depict diagnostic characters of species. They take on added taxonomic significance in the absence of the holotypes. In the cases of Sorex brevicaudus and Sorex parvus, pictures provide strong confirmation of the taxonomic identities of these two species, as well as recording the early history of the specimens.