240 DESCRIPTION OF VERTEBRATE REMAINS, CHIEFLY 



The specimen consists of the greater part of six median teeth, and four of the 

 first row of teeth on each side. The triturating surface of the plate is dull in 

 aspect, flat, but slightly impressed along the median line, and inclines forward and 

 inward on the first tooth, apparently as the result of wearing. 



The transverse sutures of the median teeth are gently curved with the convexity 

 backward. The lateral teeth are hexagonal, and nearly as broad as they are fore 



and aft wide. 



The sutures generally, but especially the outer parts of the median transverse 

 sutures and those uniting the median and lateral teeth, as well as these together, 

 are remarkable for their unusually serrulate condition. The same character 

 is remarked in Myliohates suturalis. The root surface of the specimen slopes 

 strongly on each side from the median line. The width of the plate fore and aft 

 of six teeth measures 10 lines; the breadth including the first lateral row of teeth 

 is 12| lines. The breadth of the median teeth is 10 lines; the fore and aft extent 

 of the fourth median tooth is 2 lines. 



Myliobates jugosus. 

 Leidy: Proceedings Academy Natural Sciences, Pliiladelphia, ISTG, 86. 



An isolated median tooth, represented in figures 4, 5, PI. xxxi., probably indi- 

 cates a species of eagle ray diff'erent from the former. The specimen is likewise 

 from the marl of Vincenttown, Burlington Co., N. J., and was recently presented 

 to the Academy by Col. T. M. Bryan. 



The tooth is transversely nearly straight, and the ends are angular and adapted 

 to the articulation of small hexagonal teeth as in the species of Myliobates gene- 

 rally. The crown forms a thick median transversely convex prominence with the 

 sides extended outwardly and thin. The prominence appears as an exaggeration 

 of the median ridge of the dental plate of M. fastigiatus due to the more abrupt 

 depression of the sides of the crown. The tooth at the median prominence is no 

 thicker than in the smaller of the dental plates described under the name of M. 

 fastigiatus, while it is considerably broader. The triturating surface is transversely 

 convex on the median prominence and becomes nearly flat upon its reflected sides. 

 The dull aspect of the triturating surface, and the comparatively thin condition of 

 the sides of the crown probably indicate some reduction as the result of wearing. 

 The anterior inclining surface of the crown and the projecting posterior surface 

 indicate a somewhat imbricated arrangement of the median teeth. In the specimen 

 the back of the eminence of the crown is unsymmetrical, apparently deformed. 

 The base of the crown opposite the median eminence is concave, and this curvature 

 at the sides is slightly deflected. The root is straight on its attaching surface. 



