JOS ME, C. TATE REGAN ON THE 



Key to the Species. 



I. Adipose fin composed of a well-developed, freely movable spine, posteriorly attached by a 



membrane to the caudal peduncle. 



A. Ventrals originating well in advance of the dorsal, extending ij-f of the distance from 



their base to the anal opening. 



Teeth of the outer series of the prsemaxillaries all bicuspid ; inter- 

 ocular width 3| times in the length of head 1. A. homodon Rgn. 



Lateral teeth of the outer series of the prsemaxillaries unictispid ; 



interocular width 5 times in the length of head 2. A. boulengeri Rgn. 



B. Ventrals originating nearly below the first dorsal ray, extending to the anal opening. 

 Teeth of the outer series of the pra3maxillaries mostly bicuspid ; 



length of head 3^-3J times in the total length 3. A. guentheri Blgr. 



Teeth of the outer series of the prsemaxillaries mostly uuicuspid ; 



length of head 4 times in the total length 4. A. cyclopum Humbdt. 



II. Adipose fin, if present, elongate, with or without a small spine. 



A. Outer series of teeth of the prsemaxillaries mostly uuicuspid, more or less acute; 

 mandibulary teeth bicuspid ; nasal flap not produced as a barbel. 



1. Ventrals originating below, or nearly below, the first dorsal ray. 



a. Adipose fin weakly or moderately developed ; pectoral spine not extending to middle 



of ventral. 



a. Adipose fin with a small spine which is completely imbedded in the adult; barbel 

 extending to the gill-opening, or at least | of the distance from its base to the 

 gill-opening. 

 Ventrals extending § of the distance from their base to the anal 



opening 5. A. whymperi Blgr. 



Ventrals extending |-| of the distance from their base to the anal 

 opening ; distance from base of last aual ray to caudal 4§-5 times 



in the total length 6. A. eigenmanni Rgn. 



Ventrals extending f-4 of the distance from their base to the anal 

 opening ; distance from base of last anal ray to caudal 6 times 

 in the total length 7. A. vaillanti Rgn. 



/3. Adipose fin without spine. 



Barbel extending ^~§ of the distance from its base to the gill- 

 opening 8. A. orientalis Blgr. 



Barbel extending to, or nearly to, the gill-opening 9. A. br achy cephalus Gthr. 



b. Adipose fin strongly developed ; pectoral spine extending beyond middle of ventral. 

 a. Ventrals extending to the anal opening; barbels nearly to the gill-opening or 



bevond. 



