SOUTH AMERICAN NEMATOGNATHI. 261 



Head 3J-3J; 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^E. 



ANALYSIS OF THE GENERA OF AMERICAN AUCHENIPTERIN.E. 



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



ASTEROPHYSUS XLIII. 



aa. No teeth on the vomer or palate except sometimes in C'entromochlus 

 intermedius . 



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. 



ff. Anal 19-41. 



g. Caudal obliquely rounded or slightly emarginate; 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 usually 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. 



