SOUTH AMERICAN NEMATOGNATHI. 261 



Head 3i-3i; depth 4|-5; Lat. 1. 19-21; D. I, 6; A. 

 11-13; V. 7; P. I, 10. 



Six specimens .14-. 24 m. Rio Puty. 0. St. John. 



Subfamily AUCHENIPTERIN^. 



ANALYSIS OF THE GENERA OF AMERICAN AUCHENIPTERIN^. 



a. Teeth on the palatines; cleft of month extending far past eye. V. 10. 



ASTEROPHYSUS XLIII. 



aa. No teeth on the vomer or jDalate except sometimes in Centromochlus 

 intermedins. 



b. Maxillary and four mental barbels present. 

 c. Mental barbels in two pairs. 

 d. No adipose fin. 



e. V. 15-16; body elongate; anal long; pectoral spine serrate on 

 both margins. Trachelyopterichthys xliv. 



ee. V. 6; body short; anal moderate; pectoral spine smooth on its 

 outer margin. Trachelyopterus xlv. 



dd. Adipose fin about as long as the anal fin; gill-opening con- 

 tinued below base of pectoral. Wertheimeria xlvi. 

 ddd. Adipose fin much shorter than the anal fin; gill-opening not 

 extending below base of pectoral fin. 



/. Anal short, 7-11; mouth terminal, jaws equal; caudal forked; 

 V. 6. Centromochlus xlvii. 



//. Anal 19-41. 



y. Caudal obliquelj' rounded or slightly emargiuate; outer mar- 

 gin of pectoral spine serrate. 



h. Mouth terminal, jaws equal or the lower longer; no prom- 

 inent bony orbit. Dorsal plate with or without descending 

 process. Caudal truncate or emarginate. V. 6-10. A. 19-40. 



Trachycorystes xlviii. 



hh. Mouth inferior, narrower than the snout; anterior orbital 



bones greatly developed marking an angle between snout 



and sides of head; head much broader than deep. Dorsal 



plate with a descending process behind. V. 9-10; A. 26-27. 



AUCHENIPTERICHTHYS XLIX. 



gg. Caudal deeply forked; outer margin of pectoral spine smooth 

 or granular. Head iisually covered with smooth skin. Dorsal 

 plate with a descending process behind. Upper jaw longer; 

 head longer than wide; frontal fontanel open in front. V. 8. 

 Anal emarginate, 17-21. Felichthys l. 



cc. Mental barbels arranged in a series near the symphysis. 



i. Adipose fin none; dorsal fin rudimentary, I, 3. Teeth none. V. 14. 



Epapterus li. 



