1896.] -L^'J [Cope. 



their compressed form, and for the unequal elevation of the grinding 

 surface. There is a median cusp much elevated above an external heel, 

 which is at the base of the crown ; and there is an internal cusp which 

 is fused to the median cusp, and reaches a similar elevation. It is 

 doubtful whether there are any interalveolar walls, as the teeth are 

 closely placed. 



The internal cusp is a little more elevated tlian the median, and its 

 apex is separated from that of the latter by a shallow notch. The outer 

 wall of the median cusp is vertical, while the inner wall of the inner cusp 

 is convex both verticallj' and anteroposteriorly. The worn section of the 

 two is unequally dumbbell-shaped. The external face of the median 

 cusp exhibits a median rib, with a groove on each side, besides finer 

 grooves, which are also present on the anterior faces of the crown near 

 the external border. Internal to these, the median cusp sends shallow 

 grooves obliquely inwards and downwards, which do not reach the base 

 of the internal cusp. The transverse diameter of the crowns diminishes 

 gradually posteriorly, so that the alveolus of the last one of the series is 

 small and round. 



The groove which separates the teeth from the external parapet of the 

 jaw is half as wide as the width of the molars. Its edge is roughened 

 with projections which separate fossae and foramina of difi'erent sizes. 

 The external surface of the jaw is roughened with innumerable wrinkles 

 and tubercles separated by grooves, fossaj and foramina. 



Measurements. mm. 



Length of series of nine teeth 46 



Width of crown of largest molar 13 



Elevation of external heel 5 



" internal cusp 11 



Anteroposterior diameter 5 



Width of mandibular ramus at do 26 



The specimen by which this species is known was found by Mr. J. C. 

 Isaac in 1878. It is the "No. 2 " of mj^ description of Diadeetes sidero-' 

 pelicus of the Proc. Amer. Philos. Soc, 1878, p. 505. 



DiADECTES SIDEROPELICUS Cope, loC, cU. 



T^iis species is represented by a left maxillarj- bone which contains 

 three molar teeth in place and spaces for five or six others. A simple 

 tooth at its anterior part is larger than is usual in the species of this fam- 

 ily. I have accordingly defined the genus Diadectes as characterized by 

 the presence of a canine tooth. It is, however, not possible to determine 

 whether the other simple teeth may not have been of equal proportions, 

 as they are represented by alveoli in the specimen. I therefore define 

 the genus by the molar characters, which are distinct. In this respect 

 the species D. latibuccatus and D. phaseolinus agree with it. In the last- 



