180 PROCEEDINGS OF THE NATIONAL MUSEUM vol.94 



species found only in the Maracaibo Basin. There were three genera 

 and four species. 



The Auchenipteridae are represented by one genus and one species, 

 closely related to a form in the Magdalena Basin. 



The Pimelodidae were represented by 11 genera and 13 species in 

 the Maracaibo Basin. Two of these genera have not been found else- 

 where in South America. The other genera have representatives that 

 occur outside of the Maracaibo Basin. 



The Ageneiosidae were represented by a single genus and species, 

 related to a form in the Magdalena Basin. 



In the Bunocephalidae two genera and three species occur in the 

 Maracaibo Basin and these genera are not found elsewhere in South 

 America. 



The Cetopsidae had but a single genus and species in the Maracaibo 

 Basin, and this one was related to a similar form outside the basin. 



The Pygidiidae are represented by two genera and six species. 

 A new genus and new species are especially distinctive for this basin, 

 as the subfamily to which it belongs was never before reported out- 

 side of the Amazon Basin. 



The Doradidae, not previously reported from the Maracaibo Basin, 

 were represented by a new genus and species. 



The Callichthyidae, represented by one genus and species, appear 

 to be the same as in adjoining basins. 



The Astroblepidae, with one genus and three species, had but one 

 species confined to the Maracaibo Basin. 



In the Loricariidae 12 genera and 19 species were collected, and only 

 one was a new genus as yet found only in the Maracaibo Basin. 



In this report 38 new forms are described: Four new species and one 

 new subspecies from the Orinoco system; six new genera, 16 new 

 species, and 17 new subspecies from the Maracaibo Basin. 



No attempt will be made to discuss in detail the distribution of 

 Venezuelan fishes until all the material collected by me has been 

 identified. 



TAXONOMIC SECTION 



Order NEMATOGNATHI 



Fishes without scales, bodies naked, or with bony plates; fu'st four 

 vertebrae united to form the Weberian apparatus; subopercle absent; 

 opercle weU developed or vestigial; maxillary reduced, forming the 

 basis for the maxillary barbel ; mental and nasal barbels present or ab- 

 sent; adipose fin usually present, variable, absent in certain groups; air 

 bladder weU developed or minute, united with the Weberian apparatus; 

 paired and median fins usually well developed, with certain exceptions. 



