106 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



convinced, however, that such is the case, but believe that Cope's sur- 

 mise may prove correct. Until more material is collected, the question 

 at issue cannot, I think, be satisfactorily settled. 



The dimensions of the type specimen of A?ioplonassa forcijxxta are as 

 follows : — 



Total length 191 mm. 



Greatest breadth at the posterior end 34 



" " at the anterior end (across the centre of the anterior 



pair of alveoli) 34 



Least breadth behind the anterior pair of alveoli 27 



Breadth across centre of posterior " " " 32 



Vertical depth at posterior end of fragment 29 



" " opposite the posterior pair of alveoli 26 



" " " the hind margin of the anterior pair of alveoli . 30 

 Greatest breadth between inner margins of rudimentary alveolar canal 



posteriorly 24 



Breadth between the same, midway from anterior to posterior pairs of 



alveoli 16 



Least breadth between posterior alveoli 14 



" " " anterior alveoli 4 



Length of posterior alveolus (left) 13 



Breadth " " " 1 



Length of anterior alveolus (left) 23 



Breadth " " " 16 



