242 DESCRIPTION OF VERTEBRATE REMAINS, CHIEFLY 



portions and depression of the contiguous posterior portions of the median teeth 

 as in Myliobates mordax. 



Myliobates vicomicanus. 

 Cope: Proceedings Academy Natural Sciences, 186t, 140. 



The species thus named by Prof. Cope was based on specimens found in 

 association with those attributed to M. gigas. The best preserved of the speci- 

 mens represented in figure 5, Plate xxxiii., consists of an inferior dental pavement. 

 It retains eleven median teeth, together with part of two lateral rows on one side, 

 and of one row on the other side, and measures a little over three inches in length. 

 The anterior three or four median teeth are abraded from the trituration of food. 



The plate beneath is almost straight fore and aft, and is slightly convex in the 

 same direction on the triturating surface. This is also moderately convex trans- 

 versely, but is feebly depressed along the middle. The surface is comparatively 

 even and smooth. 



The median teeth and intervening sutures are nearly straight across the middle 

 of the pavement, but present a feeble convexity backward, while the ends curve 

 backward. 



The lateral teeth have the same character as in the former specimen ascribed 

 to M. gigas, and as in this, there appear to have been but two rows on each side. 



Seven median teeth except the last in the specimen, measure together fore and 

 aft 251- lines. The fifth tooth is 31 lines wide fore and aft, and the eighth one is 

 4 lines wide. The breadth of the median teeth is 27 1- lines. 



The under surface of the dental plate slopes off on each side from the median 

 line, where the plate is half an inch thick. 



M. gigas has been characterized alone from the superior dental armature, and 

 M. vicomicanus alone from the inferior dental armature. The characters of the 

 two armatures are sufficiently alike to render it probable that they may pertain 

 to the same species. 



Myliobates pachyodon. 

 Cope: Proceedings Academy Natural Sciences, 1867, 140. 



A third species of an eagle-ray was described by Prof. Cope, under the above 

 name, from a fragment of a dental plate, represented in figure 6, Plate xxxii., 

 which was found in association with the former in Charles Co., Md. The speci- 

 men retains portions of four median teeth together with portions of several of a 

 lateral row, and in its present condition measures 1| inches long. It appears to 



