1919.] NATURAL SCIENCES OF PHILADELPHIA. 11 



1. I. to dorsal origin; snout 3| in head, measured from upper jaw 

 tip; eye 3|; maxillary 3f; interorbital 2i; least depth of caudal 

 peduncle 3|. 



Fig. 3. — Cypselurus polyethmus. 



Body elongately fusiform in contour, deepest medially, broad 

 and depressed above forward, and becoming Avell compressed 

 behind. Caudal peduncle compressed, least depth If its length. 



Head broadly depressed above, flattened sides narrowly con- 

 stricted below, width If its length, and lower profile much more 

 inclined. Snout broadly depressed, length | its wadth. Eye 

 high, large, impinging slightly on upper profile, hind pupil edge 

 slightly in advance of head center. Mouth small, with short 

 gape, and mandible slightly protruding beyond snout tip. Teeth 

 minute, feeble, only a few scattered along front edges of trenchant 

 jaws, which otherwise smooth. Mouth roof toothless. Maxillary 

 largely concealed, only narrow lower edges exposed, reaches eye. 

 Tongue smooth, depressed, moderately long, front end rounded 

 and free. Nasal cavity triangular, about half of pupil. Preorbital 

 1|- in eye. Interorbital broad, level. 



Gill-opening extends forward to nasal cavity. Gill-rakers 

 9 4-21, lanceolate, very slightly less than filaments which If in 

 eye. Isthmus slender frenum in front. 



Scales large, very caducous, cycloid, rather narrow^ly exposed, 

 largest anteriorly on back and head above, basal radii 4 to 6, 

 circuli complete, about 36 to 40. Dorsal and anal apparently 

 scaleless, though caudal base scaly. Head covered with scales, 

 though apparently edge of snout rather broadly naked. Breast 

 covered with moderately small scales. 



Dorsal origin about last third in space between hind gill-opening 

 edge and caudal base, front rays a little elevated. Anal inserted 



