242 CALIFORNIA ACADEMY OF SCIENCES. 



Astrodoras asterifrons Bleeker, Nederl. Tijd. Dierkuiide, i, 1863 



(name only). 

 Habitat: Amazon, Solimoens and tributaries. 



Wide and depressed in. front, the depth below the dor- 

 sal spine scarcely more than half its width; the depth at 

 the caudal peduncle equal to its width. Breast very 

 wide, the width between the outer margins of the clavi- 

 cles equal to the distance from the snout to the dorsal 

 spine. Head short and pointed, its width equal to its 

 length; its depth 1J in its length. Bones of the head 

 with series of fine granules; dorsal plate ending in a 

 sharp process on either side behind the dorsal spine. 

 Posterior portion of the head with a strong median keel. 

 Supercilliary ridges raised, the interorbital area deeply 

 concave; suborbital bones and preopercle granular; 

 nasal bones forming a high crest which is deeply pecti- 

 nate. Fontanel extending scarcely beyond the middle 

 of the eye, continued as a groove along the median keel. 



Eye well protected, 1J-2| in the snout, 4-5 in the 

 head, lf-2 in the interorbital. 



Maxillary barbels reaching beyond the middle of the 

 pectoral spine; mental barbels little more than half as 

 long as the postmental which reach somewhat beyond 

 the base of the pectoral spine. 



Snout narrow, its width at the rictus 2-2 J in the head; 

 jaws equal, or the upper little longer; teeth in narrow 

 bands. 



Gill-opening extending forward to below the eye; cor- 

 acoid bones exposed below, striate in front, the points of 

 the processes sharply granular. 



Two small granular plates on the humeral region; the 

 first and second hook-bearing lateral scutes touch the 

 dorsal plate, the fifth lateral plate highest, 1J in the 

 head, gradually decreasing in height backward, but 

 leaving only a narrow naked area on. the back. Each 

 scute with one or two marginal spines below and three 



