250 DESCRIPTION OP VERTEBRATE REMAINS, CHIEPLT 



is convex. The outer lateral border presents a single denticle a short distance from 

 the summit. The root extends below the crown with a prominent obtuse convex 

 border, and projects backward in a broad trilobate base, as seen in figure 9. 



Length of the tooth in front, 4f lines; breadth, 3^ lines. Length of the crown 

 in front, 3| lines. Height of base of root posteriorly, 3| lines; breadth, 3| lines. 



ACRODOBATIS.* 



ACRODOBATIS SERRA. 



Among the fish teeth occurring in collections of fossils from the Ashley phos- 

 phate beds, I have noticed a number which appear to pertain to a species of Eay. 

 Teeth of the kind are represented in figures 10-13, Plate xxxiv., twice the natural 

 size. They may perhaps be symphysial teeth of a Shark. 



The crown of these teeth is usually wider than high, and the base is extended 

 downward at the middle in a rounded prominence, and backward posteriorly in a 

 similar prominence. The summit rises in a tapering point, and the lateral acute 

 borders exhibit seven or eight denticles successively decreasing towards the base. 

 The teeth of figures 10, 11, have the main point worn off and the lateral denticles 

 more or less abraded. The tooth of figure 12 has the main point partially worn 

 off", and even that of fig. 13 has the extreme point somewhat blunted by abrasion. 



The root of these teeth is a shallow basis with a trilateral outline, the angles 

 rounded and the lateral ones slightly projecting. 



ACRODOBATIS OBLIQUUS. 



Figure 14, Plate xxxiv., represents a tooth nearly like those just described, 

 but having the main point directed to one side so as to recall to mind the teeth of 

 Galeocerdo. The specimen was obtained in the marl of Monmouth Co., New Jer- 

 sey, and was presented to the Academy by Dr. Knieskern. The inner acute border 

 of the crown is the longer, and is convex in its course from the base of the main 

 point. It presents seven denticles successively decreasing in size. The outer side 

 presents two larger denticles succeeded by four minute ones. The construction of 

 the base of the crown is like that of the preceding teeth. 



Length of the tooth, 3 lines; breadth, 3j lines; thickness at base, 2f lines. 



I have regarded the tooth as representing a species -distinct from that to which 

 the Ashley fossils pertain, under the name above given. 



* Contracted from Acrodontobatis. 



