280 CALIFORNIA ACADEMY OF SCIENCES. 



Auchenipterus immaculatus Cuv. & Val. Hist. Nat. Poiss. xv, 218, 



1840 (Cayenne). 

 Auchenipterus punctatus Cuv. & Val. Hist. Nat. Poiss. xv, 219, 1840 



(? Brazil); Kuer, SB. Ak. Wiea, xxvi, 425, 1857 (Eio Branco). 

 Auchenipterus lacustris Ltitken, Dan. Selsk. Skr. 1875, .5 , 148, with 



fig. (Kio das Velhas). 

 Habitat: Rio San Francisco to the Orinoco. 



Robust, somewhat compressed. Head short, chubby 

 width of the head as great as, or greater than its length 

 width of the mouth l|-lf in the length of the head 

 depth at the occipital process about equal to the length of 

 the head. Bones of the head and humeral process gran- 

 ular. Occipital process with its sides emarginate, with 

 rather long backward projecting processes which are not 

 curved downward behind, its least width more than 

 twice its least length. Fontanel pear-shaped, open in 

 front in the young, becoming reduced to a small round 

 opening between the frontals in the old. 



Eye If in snout, 6 in head, 4i in the interocular. 



Lower jaw considerably longer; teeth all short, villi- 

 form or setiform, intermaxillary band very shallow, its 

 depth 10 in its width. 



Maxillary barbel reaching tip of humeral process or a 

 little farther; mental barbel about half length of head, 

 postmental reaching a little beyond base of pectoral. 



Gill-opening not extending below base of pectoral. 

 Humeral process variable in length, always reaching be- 

 yond middle of pectoral. Pectoral pore present, well 

 forward. 



Distance of dorsal spine from snout 2|-3 in the 

 length; dorsal spine varying in height, 1-lf in the head, 

 its anterior margin almost smooth, granular, or with 

 rather sharp teeth, its posterior margin sometimes with 

 distinct teeth, sometimes almost smooth; first dorsal ray 

 usually somewhat higher than the spine. 



Distance between dorsal and adipose fins 2^-23- in the 



