1913.] NATURAL SCIENCES OF PHILADELPHIA. 521 



stricted above or below, so that these surfaces equally broad and 

 convex. Snout convex over surface and in profile, length about 

 f its width, and as viewed from above broadly convex. Eye large, 

 rounded, high, centre falls about first f in head. Pupil large. Adi- 

 pose eyelid large and covers good portion of eye. Mouth broadly 

 transverse, with shallow horizontal commissure extending about 

 opposite front nostril. Snout tip protrudes well beyond upper jaw 

 edge. Jaw edges rather trenchant, cartilaginous, firm, and without 

 lips. No teeth. Mandible shallow, broad, with slight symphyseal 

 knob fitting in depression in upper jaw. Inner buccal folds narrow. 

 Tongue broad, as transverse cartilaginous truncate keel in front, 



Prochilodus pterostigma Fowler. (Type.) 



otherwise fleshy or thick and its extent ill defined. Maxillary small, 

 extends down obliquely in short fleshy point below until opposite 

 front nostril. Nostrils together, anterior simple pore and posterior 

 exposed in crescent, placed at last third in snout length. Inter- 

 orbital broadly convex. Suborbitals broad, well developed, infra- 

 orbital entirely covering cheek and its surface with a few obsolete 

 striae. Four large mucous tubes on preopercle, and its hind edge 

 very slightly inclined back. Opercle large, with a few obsolete radi- 

 ating striae. Occipital fontanel quite long, extends from just behind 

 posterior nostrils to end of occipital process, and widens gradually, 

 from in front backward, its entire length. 



Gill-opening extends forward about opposite posterior edge of 

 pupil. Rakers about 10+20? short weak points, uniform in 

 35 



