226 CALIFORNIA ACADEMY OF SCIENCES. 



Depth below the dorsal spine about equal to the width. 

 Caudal peduncle slender, not as wide as deep. Head 

 little shorter than wide, its depth equal to its width. 

 Humeral process, upper half of ppercle, suborbitals, pre- 

 nasal and bones of the top of the head all rather finely 

 granular. Interorbital area flattish, the head becoming 

 more and more roof-shaped backwards to the dorsal 

 plate which has its sides very steep. The postorbital 

 portion of the profile arched. Dorsal plate not prolonged 

 behind the first dorsal ray but with a strong descending- 

 process behind. Superciliary margins not raised, deeply 

 emarginate; the prenasal bone large and roughened 011 

 its edge. Fontanel a narrow slit about as long as the 

 eye, situated in a clavate depression. A marked groove 

 extends from it to the tip of the dorsal plate. 



Eye well protected by dermal ossification ; 2-1 J in the 

 snout, 4J-6 in the 'head, 2-2J in the interorbital. 



Maxillary barbels about reaching the tip of the 

 humeral process, somewhat longer in the young and 

 somewhat shorter in the adult; postmental barbels not 

 reaching to the base of the pectoral spine; mental 

 barbels 3 or 4 times as long as the eye. 



Snout rather narrow, covered with short papillae, its 

 width at the rictus 2J in the head. Upper jaw project- 

 ing; teeth all villiform, the intermaxillary band 5 times 

 as wide as deep. 



Gill-membranes separate to below the middle of the 

 opercle; breast entirely covered with skin. 



First two or three lateral plates touching the dorsal 

 plate above, the last one of them 'highest, those behind 

 it decreasing in height to the last, the median hooks 

 increasing in strength from in front backward to those 

 on the middle of the caudal peduncle. A series of plates 

 of varying sizes between the dorsal and the caudal; 

 usually a plate on each side of the adipose fin which 



