A series of synapomorphies for the characiform family Chilodontidae, in addition to those proposed by Vari (1983), are discussed. These involve modifications of the suspensorium, hyoid arch, infraorbitals, lower jaw, supraorbital portion of the laterosensory canal system in the frontal, and lateral-line scales. The chilodontid genera Chilodus Miiller and Troschel (1844) and Caenotropus Giinther (1864) are diagnosed as monophyletic on the basis of derived features of the third postcleithrum, lower jaw, hyoid arch, pterotic, supracleithrum, and the laterosensory canal systems in the infraorbitals, frontal, and posterior lateral-line scales. Modifications of a subset of those systems, the subopercle, dentition, suspensorium, third postcleithrum, and pigmentation define subunits of Caenotropus or are autapomorphic for its species. Caenotropus is revised, with Tylobronchus Eigenmann (1912) considered a junior synonym. Three Caenotropus species are recognized: C. labyrinthicus (Kner, 1858) widely distributed in the Rio Amazonas and Rio Orinoco basins, the upper Essequibo River basin in Guyana, the Saramacca and Suriname Rivers in Suriname, and the Rio Parnafba, northeastern Brazil; C. maculosus (Eigenmann, 1912) ranging from the Essequibo River of Guyana to the Fleuve Maroni of French Guiana; and C. mestomorgmatos, new species, from the acidic black waters of the middle and upper Rio Negro in Brazil and Venezuela and the upper Rio Orinoco in southern Venezuela. Chilodus labyrinthicus rupununi Fowler (1914) is placed into the synonymy of Caenotropus labyrinthicus. Keys are provided to the genera Caenotropus and Chilodus and to the species of Caenotropus. A lectotype is designated for Microdus labyrinthicus Kner. The biogeographic implications of the geographic distribution of subunits of the Chilodontidae are discussed. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The coral Montastrea cavernosa (Linnaeus).

The Neotropical auchenipterid catfish genus Auchenipterichthys is reviewed and found to include four species. Auchenipterichthys thoracatus, formerly considered to be widely distributed throughout the Amazon River basin, is found to be restricted to the upper Madeira River basin. The widespread Amazonian species that had been misidentified as A. thoracatus is, instead, A. coracoideus; a species that also occurs in the upper Essequibo River. Auchenipterichthys longimanus, the most widely distributed species of the genus, is found through much of the Amazon and Orinoco River basins. The fourth species of the genus, A. punctatus (and its junior synonym A. dantei), is found in the upper portions of the Orinoco and Negro River basins in Venezuela and the central portions of the Amazon River basin in Brazil. All four species of Auchenipterichthys are redescribed and illustrated, and a key to the species is provided. O gênero Neotropical Auchenipterichthys de Auchenipteridae é revisado, incluindo quatro espécies. Auchenipterichthys thoracatus, anteriormente considerado como largamente distribuído na bacia do rio Amazonas, é restringido para a região superior da bacia do rio Madeira. A espécie amazônica largamente distribuída e que tem sido identificada erroneamente como A. thoracatus é, ao invés disto, A. coracoideus; uma espécie que ocorre igualmente na região superior do rio Essequibo. Auchenipterichthys longimanus, a espécie de maior distribuição no gênero, é encontrada nas bacias dos rios Amazonas e Orinoco. A quarta espécie do gênero, A. punctatus (e seu sinônimo júnior A. dantei), é encontrada nas porções superiores dos rios Orinoco e Negro na Venezuela e porção central do rio Amazonas no Brasil. Todas as quatro espécies de Auchenipterichthys são redescritas e ilustradas, e fornecida uma chave para a identificação das especies.

Herein we consolidate the information available concerning the biodiversity of batoid fishes in the northern Gulf of Mexico, including nearly 70 years of survey data collected by the National Marine Fisheries Service, Mississippi Laboratories and their predecessors. We document 41 species proposed to occur in the northern Gulf of Mexico. However, the validity of several of these reports and their associated data is questioned. In addition, we provide information and remarks concerning the distribution, conservation status, taxonomy and recorded history for each species covered.

The first cases of spinal abnormalities for the common angel shark Squatina squatina in the Canary Islands (Spain), are reported. Two specimens, a juvenile and an adult female with 21º and 42º of scoliosis were recorded in Tenerife and Gran Canaria islands, respectively. Possible causes are discussed.