1914.] 



NATURAL SCIENCES OF PHILADELPHIA. 



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plate of latter, junction indicated by slight angle. Median lateral 

 keel at first obsolete, though after dorsal very distinct and con- 

 tinued as lateral flange to caudal. Lower lateral keel extends from 

 plate of shoulder-girdle back to twenty-second plate of median 

 (then upper) keel, where it merges without an interruption. Before 

 each ventral origin slight lengthwise keel. Caudal peduncle ex- 

 tremely long, depressed, broad, and tapering. 



Head rather small, sides convexly approximated above, lower 

 surface broadly convex. Snout greatly acuminate, narrowed tip 

 produced, width at front of eyes If its length. Eye small, a little 

 ellipsoid, high, slightly posterior to last third in head measured to 

 hind edge of occipital plate. Edges of eyes free, without membrane 



Fig. 18. — Slurisoma monopelte Fowler. (Type.) 



covering over. Mouth width broad, forms rather large rounded 

 disk, and transverse mouth cleft would form about last third in 

 snout length. Lips very broad and greatly papillose, and papilljB 

 bordering jaws much larger. About 66 small, simple, slender, 

 clavated, and slightly crooked teeth in transverse series in upper 

 jaw, and about same number of similar ones, more bent over at 

 ends, in lower jaw. Ramus of mandible slightly less than eye. 

 Upper jaw with 3 fleshy papuliferous flaps inside, median much larger. 

 Inner buccal fold very broad and free. Externally each side of disk 

 forms small pointed barbel. Nostrils in moderate-sized depression, 

 together, formed just before front orbital edges, anterior with broad 

 cutaneous flap mostly concealing posterior. Interorbital generally 

 level, with lengthwise shallow depression each side of median line. 

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