ELASMOBRANCHII. 



79 



Outer basal surface rarely with several short wrinkles. Apex 

 deflected more or less laterally, slender-pointed. Cutting-edges 

 finely serrated and seme of about more or less even size. Lat- 

 eral coronal margins long, but little less than rest of crown itself 

 when measured to notches, and low. Serras always more or less 

 conspicuous on these lateral crown margins, even when obsolete 

 or absent on coronal margin above notches. No basal cusps. 

 Root compressed, usually wide, conspicuous, depressed or con- 

 cave externally, and inside swelling slightly convex. Ends of 



Fig. 38. — Sphyrna prisca Agassiz. Charles Co., Md. (Thomas). 



roots widely diverging, so that lower edge is concave or at least 

 slightly notched medianly. Length reaches 15 mm. This de- 

 scription from a series of examples from the Maryland Miocene. 

 This species is close to Glyphis egertoni, and possibly ma- 

 terial identified with it may belong to that species, but, following 

 Cope, I have allowed it all to fall with the present provisionally. 

 The crown in most of the examples is conspicuously narrow or 

 small, and the root is mostly very wide. Several examples with 

 extremely wide roots suggested a new species to Cope, but they 



