ELASMOBRANCHII. 43 



Body short, stout, back somewhat elevated. Snout prominent, 

 pointed. Teeth triangular, pointed, entire, each with one small 

 basal cusp on each side, though cusps sometimes obsolete on 

 some teeth in young. Gill-openings wide. First dorsal and pec- 

 toral fins somewhat falcate, former close behind pectoral bases. 

 Second dorsal and anal very small, nearly opposite one another. 



Large fierce sharks in most cool seas, to which three existing 

 species and about 34 extinct have been referred. 



Lamna cuspidata Agassiz. 



Lamna cuspidata Leidy, Proc. Acad. Nat. Sci. Phila., 1872, p. 166. (Prob- 

 ably New Jersey Cretaceous.) 

 Cope, Proc. Am. Philos. Soc. Phila., XIV, 1875, p. 362. (Cumberland 

 Co. Miocene.) 



Lamna denticulata Cope 1. c. (Cumberland Co. Miocene.) 



Anterior teeth usually long, slender, compressed and moder- 

 ately triangular, scarcely sigmoid in character. Crown usually 

 slender, subulate, erect or sometimes diverging outwards. Outer 

 coronal surface flattened or but slightly convex, smooth. Inner 

 coronal face usually well convex, sometimes little flattened 

 medianly, and entirely smooth. Apex erect or variously de- 

 flected. Cutting-edges prominent, entire. Usually one, sometimes 

 two, small acute basal cusps on one or each side. Root larg'e, 

 outer face concavely depressed, and inner convexly bulging till 

 very pronounced, the convexity usually with more or less complete 

 sulcus. Branches of root usually long, moderately divergent, 

 and angle between branches usually well marked. Lateral teeth 

 broader, shorter, especially crowns, which are often well de- 

 flected, wider angle between branches of base and basal cusps 

 varying quite broad. Length reaches 43 mm. 



This is a very common fossil in the New Jersey marls and I 

 have examined many teeth. This species is known only from 

 detached teeth, scarcely distinguishable ,in many instances from 

 those of Isurus acuminatus. The teeth may also be confused, 

 with those of other related sharks, though they do not appear 

 to reach quite so large a size as the well-marked Lamna elegans. 

 From I sums desorii it may often be distinguished by the pres- 



