1911.] 



NATURAL SCIENCES OF PHILADELPHIA. 



495 



similar, nearly straight. Snout broad, obtuse, convex both over 

 surface and in profile, produced well beyond mandible tip, and 

 length about f of basal width. Eye nearly circular, but little 

 elevated, and centre well before middle in head length. Eyelid 

 narrow. Mouth broad, and commissure short in profile, horizontal 

 largely. When opened, mouth quite broad, directed downwards, 

 and jaws rather firm and but moderately strong, apparently not 

 disk-like. Lips thin and scarcely developed, edge of upper rather 

 trenchant and lower rather broad. Edge of each lip with a row of 

 numerous minute papillae its whole extent, and apparently all sessile. 

 No inner series in either jaw. Mouth aperture small, as seen in 

 front with a medium notch in upper jaw into which symphysis 



Fig. 1. — Prochilodus stigmaturus Fowler. Type. 



of mandible fits. Also each ramus of mandible swollen a little on 

 its upper edge, this fitting in a corresponding concavity also in side 

 of upper jaw. Upper and lower buccal folds moderately broad in 

 mouth. Tongue small, fleshy, not free. Mandible short, and rami 

 well elevated inside mouth, articulated below hind nostril. Nostrils 

 moderate, close together, anterior circular and about midway in 

 snout, and posterior exposed in crescent close behind. Interorbital 

 space broadly convex. Preorbital about 1^ in eye. Infraorbital 

 narrow, about equals eye. Postorbital width If in eye. Pre- 

 orbital also a little swollen, with cavity below, into which maxillary 

 fits when closed, its hind edge then about opposite nasal frenum. 

 Opercle width about If its depth and smooth like other bones of 

 head. Cutaneous opercular flap moderately broad behind. 



