238 DESCRIPTION OP VERTEBRATE REMAINS, CHIEFLY 



tooth is 18| lines; its thickness 4 lines. The width of the crown fore and aft is 3 

 lines; the thickness at the middle is 2| lines, and at the ends 1| lines. 



Another isolated median tooth, represented in figures 6, 7, PI. xxxi., is from 

 the same locality and donor as the preceding specimen. With the exception of a 

 slight unsymmetrical bend forward of one end, the tooth is straight, with the 

 triturating surface transversely convex and even. The ends of the tooth are angu- 

 lar, and the bottom of the crown and the root are straight transversely. The 

 breadth of the crown is 2 inches; its width fore and aft 5 lines; its thickness at 

 the middle equals the width, and it diminishes to 3 lines at the ends. The tooth 

 including the root is 7 lines thick at the middle. 



The dental armature of Myliohates obesus, in the form and convexity of the 

 median teeth, resembles that of M. Dixoni, Ag., from the eocene of Bracklesham, as 

 represented in figures 1, 2, Tab. x., of Dixon's Geology of Sussex. The teeth in 

 the latter appear generally to be of greater width fore and aft. 



Myliobates fastigiatus. 



Leidy: Proceedings Academy of Natural Sciences, Philadelphia, 1876, 86. 



A specimen, represented in figure 6, PI. xxxiii., of the dental armature of an 

 eagle ray, differs from any which I have seen described, and may perhaps indicate 

 a species different from any previously indicated. It is from Monmouth Co., N. J., 

 probably from the " upper marl bed," or eocene green sand, and was presented to 

 the Academy by William Cleborne. 



From the arching form of the specimen it is to be viewed as having belonged to 

 the roof of the mouth. It is composed of nine median teeth with the addition of 

 some of the small teeth of the first row on each side. The fore part of the pave- 

 ment extending to the third median tooth is much abraded from the attrition of 



food. 



The pavement is well arched fore and aft, and in its present state measures 

 three and one-third inches with a little less breadth. The triturating surface 

 forms three longitudinal convex ridges, of which the intermediate one is the broader 

 and more prominent. Broad shallow valleys separate the ridges, and the lateral 

 ones of these include the small teeth. 



The transverse median sutures curve backward on the median ridge and for- 

 ward on the lateral ridges. The median teeth are three inches broad, and about 

 five lines wide fore and aft. Their free surface is nearly even, but is feebly 

 wrinkled in the valleys and upon the lateral ridges of the dental pavement. 



