396 CALIFORNIA ACADEMY OF SCIENCES. 



Body comparatively elongate, the head depressed but 

 not very broad, somewhat broader than high; eye rather 

 large, 5 to 6 in length of head; width of interorbital 

 space, 2% in head; breadth of mouth, 2|; length of 

 snout, 3. 



Teeth all villiform; bands of vomerine teeth separated 

 by a rather wide interval, each small, roundish, confluent 

 with the neighboring palatine band, the junction marked 

 by a slight constriction; palatine bands ovate, broad be- 

 hind, varying considerably in size and somewhat inform, 

 the width ranging from one-third diameter of eye to two- 

 thirds, being generally largest in adults; band of palatine 

 teeth without backward prolongation; band of maxillary 

 teeth rather broad and short, its length about five times 

 its breadth. Maxillary barbel broad and flattened at 

 base, reaching a little past base of pectoral in the young, 

 scarcel}^ to the gill opening in the adult; outer mental 

 barbels, 2 in head, inner 3. Gill-rakers, 4 -(-12. 



Dorsal shield very short, narrowly crescent-shaped, its 

 length on the median line not more than half that of one 

 of its sides. Occipital process subtriangular, not quite 

 as long as broad at base, with a strong median keel, its 

 edges slightly curved. A short distance in front of the 

 beginning of the keel is the end of the very narrow groove- 

 like fontanelle, which is somewhat widened anteriorly, 

 finally merging into the broad, flat, smooth interorbital 

 area, the boundaries of which are not well defined; shields 

 of head usually smooth, all finely and very sparsely gran- 

 ular, the granules not forming distinct lines. 



Gill membranes forming a rather broad fold across 

 isthmus. 



Dorsal spine long, usually, but not always, shorter than 

 the pectoral spine, about i^ in head; axillary pore ab- 

 sent. Humeral process rather broadly triangular, not 



