EXTINCT MAMMALIA OF NORTH AMERICA. 417 



of the present work, from the miocene marl of Shiloh, Cumberland Co., New Jersey. 

 From the teeth oi Basilosaurus, and others of the same family that I have had the 

 opportunity of inspecting, they differ in the remarkably rugose character of their 

 crown. 



The crowns of the teeth are broader than long, and nearly half as thick as the 

 breadth. They are compressed conical, with subacute bordei's and convex sides 

 somewhat impressed at the middle towards the base. The enamel, except at the 

 summit, is remarkably rugose longitudinally, especially towards the base, where the 

 rugge becomes more or less interrupted, but finally subside at the verge of the fangs. 

 In one specimen, figure 6, the anterior border is simply subacute and roughened ; 

 the posterior border forms a series of three large conical tubercles, and perhaps pos- 

 sessed a fourth. In the other specimens, figures 4, 5, the anterior border presents two 

 tubercles, and the traces of a third at the base; the posterior border possesses a series 

 of four tubercles. These tubercles partake of the general character of the crown, 

 having subacute and denticulate borders. The teeth possess a pair of fangs, connate 

 about half their length, and with their free portions having a more or less backward 

 direction. 



The teeth above described bear a lesemblauce in size and general form and con- 

 struction with the true molars of Squalodon antverpiensis, described by Van Beneden, 

 page 70 of the Mem. de I'Acad. Roy. d. Sc. de Belg. 1865, and represented in plate I; 

 and indeed^ it was the view of this plate which led me to assign the New Jersey 

 fossils to the same genus. They, however, differ in well marked characters from 

 those of S. antverpiensis. The crowns of the teeth of S. atlanticus are bi'oader in 

 relation with their length, are provided with accessory denticles on the anterior as 

 well as the posterior border, and have the enamel wrinkled in a remarkable degree. 

 In S. antverpiensis the external surfaces of the crowns of the molars appear more 

 regularly longitudinally striated, or perhaps are rather subdivided into narrow planes 

 or shallow grooves separated by narrower longitudinal ridges, with comparatively 

 little or no intervening wrinkling. In one of the teeth above described, the outer sur- 

 f\ice, or that opposed to the one represented in figure 6, is feebly subdivided into 

 narrow planes, and the wrinkling is not so strong as on the internal surface. 



The measurements of the three teeth are as follow : 



Length of crown at middle, ..... 



Breadth of crown at base, ..... 



Thickness of crown in advance of middle, 

 Lengtli of fangs from crown, ..... 



Since writing the foregoing, Prof Cope has described some remains, apparently of 



53 



ines. 



Lines. 



Lines. 





9J 



9 



12 



12J 



12 



U 



6 



5i 



20 



18i 



13* 



