118 CALIFORNIA ACADEMY OF SCIENCES. 



78.4. Pimelodus grunniens Humboldt, Rec. Observ. 

 Zool. 127, 1833 (Orinoco). Olivaceous above, spotted 

 with black; white below. Head obtuse truncated, 4 in 

 length of body; body compressed. All fins except caudal 

 olivaceous, margined with red. Adipose dorsal small; 

 barbels 6. The plaque of the neck large. Pectoral fins 

 longer than the others. The Indians call it " Carxaro." 

 2 feet 2 inches. 



ANALYSIS OF THE SPECIES OF RHAMDIA. 



a. Occipital process and fontanel wanting. ( ?) 



b. Dorsal fin more than twice as high as long, the first ray highest. 

 Snout somewhat pointed; eye 5 in head, less than 2 in the inter- 

 ocular, more than 2 in snout; posterior nasal opening nearer edge of 

 mouth than to the eye. Upper jaw somewhat the longer. Maxillary 

 barbels reaching anal, postmentals to last third of the pectoral fin. 

 Dorsal spine smooth, ending in a filament; adipose fin very long; 

 pectoral spine flattened, its inner margin serrated, teeth near tip of 

 its outer margin, reaching to below beginning of the dorsal; a small 

 pectoral pore. Caudal deeply forked, the upper lobe somewhat 

 longer, 5 in the length. Uniform brown. Head 6^ in the total 

 length. D. I, 6; A. 12. (Kner.) breviceps 79. 



aa. Occipital process present. 



c. Fontanel not continued behind the eye in the adult;* sometimes a 

 small round fontanel at the base of the occipital process. 



(KHAMDIA.) 



d. Mandible projecting beyond the intermaxillary. 



e. Head depressed. Dorsal and pectoral spines serrated. Opercle 

 striated. Adipose fin very large; vent about the middle of body. 

 Bluish-green with lighter spots; nearly white on belly and lower 

 part of head. D. I, 6; A. 12; Br. 8. (Schomburgk.) 



schomburgkii 80. 



ee. Caudal portion of the body considerably deeper than the abdom- 

 inal. Eye 2 in the interocular. Maxillary barbels extending 

 beyond the caudal, postmentals to below middle of dorsal fin. 

 Dorsal spine very slender, smooth, shorter than the pectoral 

 spine; adipose fin 4.3 in the length; pectoral spine finely serrated 

 on both edges, as long as the snout and half the orbit; supra-occi- 

 pital process six times as long as wide, not reaching to the basal 

 bone of the dorsal spine. Head 3 in the length; depth of cau- 

 dal portion of body 6^,; D. I, 6; A. 9. (Cope.) bathyurus 81. 



*Not examined in schomburgkii, batfiyurus.foina, humilis, cinerascens,pentlandi, multiradi- 

 atus, longicauda, dorsalis. 



