10 



Measurements. m. 



Length of tooth .0130 



( antero-posterior 0040 



Diameter at base \ . nnnA 



I transverse 0024 



Length of crown 0100 



It is probable that portions of skeleton of this reptile are in my 

 possession, but the means of positive identification are yet wanting. 



Compsemys imbricarius, sp. nov. 



This species, like the others of the genus, has the scutal sutures 

 well defined, and the superficial surface of the carapace sculptured. 

 The character of this sculpture distinguishes the species, and in 

 the present instance in a special manner. It consists, in the 

 G. imbricarius, of excavations bounded on the sides by a short 

 ridge each, which alternate with each other. Thus each bounding 

 ridge terminates abruptly at the fundus of one of the fossae, while 

 the other end of the fossa rises and contracts to another ridge. 

 The result is precisely that seen in the interior sculpture of Sara- 

 cenic domes or niches, and is one which is quite unique among 

 tortoises. The direction of the ridges is at right angles to the 

 costal dermal sutures. This species was about as large as the 

 snapping tortoise ( Ghelydra serpentina). 



Measurements. m. 



Thickness of a costal bone 0050 



c lengthwise .... .0065 



Three fossae measure < ■ aaka 



( crosswise 0050 



Compsemys variolosus, sp. nov. 



One of the most abundant, and the largest species of the Fort 

 Union beds. The carapace is convex and the plastron flat ; the 

 marginal bones are heavy and strongly convex on the inferior 

 side. The margin of the plastron is thickened and heavy, char- 

 acters which also belong to all parts of the carapace. The sutures 

 of the dermal scuta are deeply impressed, and the surface of the 

 bone is strongly sculptured above and below, and even on the 

 superior face of the thickened margins of the free lobes of the 

 plastron. The sculpture consists of round fossse, which are deeply 

 impressed and are arranged quincuncially, so that their borders 

 never form straight lines. The latter are also more or less angu- 

 late on the edge, so that the surface has a more than usually ru- 

 gose character. 



