2(54 



teeth, ends in a triangular process with a* Lozenge-like articular surface for 

 symphysial attachment with the bono of the opposite side. 

 Measurements derived from seven specimens are as follows: 



Measurements. 



Spec. 1. 



Spec. 2. 



Spec. 3. 



Spec. 4. 



Spec. 5. 



Spec. 6. 



Spec. 7. 



Length of series of five teeth 



Lines. 



Lines. 



Lines. 



Lines. 



Lines. 



7| 



G 



H 



n 



24 



2 



2£ 

 2 



Lines. 



7 



G 



H 



1 



2£ 

 2 

 -2 



Lint . 



Length of series of four teeth, exclud- 

 ing the first . 



15* 

 12 



12 

 10 



8 



9 



7 



5 



Length of series of intei'inediate three 

 teeth -• 



4 



Length of series of anterior three teeth. 





Long diameter of crown of first tooth . . 













Long diameter of crown of second tooth. 

 Short diameter of crown of second tooth. 

 Long diameter of crown of third tooth . 



4£ 

 3f 



*4 



H 

 H 



3 

 3 



2 



20* 

 14£' 



3f 

 2£ 



44 

 2| 

 4 



24 



3 



2J 



34. 



2£ 

 3 



2 



24 

 12 



Short diameter of crown of third tooth . 





4 



14 

 l* 



Long diameter of crown of fourth tooth. 



5 



H 



Short diameter of crown of fourth tooth. 







-*-2 



1 



Long diameter of crown of fifth tooth. 







1 



Short diameter of crown of fifth tooth. 













# 



Length of lower branch from back of 

 pharyngeal 



■ 24* 



17* 

 14 



17 



Hi 

 10 



16 



11 

 6 



14 



10 

 81 



11 



8 



10i 



Depth of upper branch to bottom of 

 pharyngeal * 



J -"i> 



Width of pharyngeal interiorly .». 



7 



Estimated. 



Family jRai«. 



ONCOBATXS. 



Oncobatis pentagonus. 



An extinct ray, before alluded to, is indicated by a single dermal bone, of 

 which two views are given, of the natural size, in Figs. 18, 19, Plate XVII. 

 The bone has a pentagonal outline with curved margins, with the under or 

 inner surface strongly convex and smooth. The upper or free surface presents 

 five sloping planes more or less well defined by prominent borders. ■ Less 

 than half the extent of the external surface at the center is occupied by an 

 areola of thin enameloid substance which is smooth and shining and marked 

 with concentric lines. The summit of the bone, in. the center of the areola, 

 projects as a point of harder and more translucent osseous substance. 



