454 GEOLOGICAL SUEVEY OF THE TEERITOKIES. 



Ileasurements. 



M. 



Width of costal bone , 0230 



Thickness of costal bone 0033 



Number of pits in 0™.010, 6. 



Liguite Cretaceous of Colorado; also several fragments from Long 

 Lake, Nebraska, from Dr. Hayden. 



PlASTOMENUS (^) INSIGNTS, Sp. nOV. 



Eepreseuted by a portion of the right byposternal bone of a tortoise 

 about the size of the last species, and from the same locality. The speci- 

 men resembles in its sculpture such species as the Plastomenus triony- 

 cJwides, and in structural character the species of Anostira, but it is 

 scarcely probable that it belongs to either genus. It is flat, and has a 

 narrow, straight, inguinal margin at right angles to the fine suture with 

 the hyosternal. The suture with the postabdomial is partially gom- 

 phosial. Surface dense, polished, marked externally with a reticulate 

 sculjiture of narrow ridges separating larger and smaller areas wider 

 than themselves. Marginal edge thinner. 



Measurements. 



M. 



Length of hyposternal fore and aft 025 



Thickness of hyposternal at front 1 „. • 004 



Pits in 0™.010, 6. 



Lignite Cretaceous of Colorado. 



ADOCUS, Cope. 



Proceedings Academy of Natural Sciences, Philadelphia, 1868, 235 ; Proceedings Amer- 

 ican Philosophical Society, 1870, November. 



ADOCUS (?) LINEOLATUS, Sp. noV. 



Established on a number of fragments from different exposures of the 

 lignite beds — primarily on a vertebral and sternal bone from the same 

 locality as the preceding specimen. As the diagnostic portions of this 

 specimen are wanting, it is referred to this genus provisionally, and 

 because the structure and sculpture of the parts resemble most nearly 

 known species of it from the Cretaceous greensand of ISTew Jersey. 



The sternal bone is flat, and presents the wide and transverse sutures 

 forming the usual right angle, and of a rather coarse character of a 

 medium serrate keel, with pits on each side for the reception of corre- 

 sponding ribs. The vertebral bone is rather thick, and is shallowly 

 emarginate in front. The sculpture consists of delicate, obscure, parallel 

 lines, which are more or less interrupted and occasionally joined, so as 

 to inclose faintly-marked areolae. 



Measurements. 



M. 



Width of vertebral bone in front 0135 



Greatest of vertebral bone ., 0280 



Thickness of vertebral bone 0070 



Thickness of sternal bone 0080 



From lignite of Colorado, and mouth of Big Horn Eiver, Montana. 



COMPSEMYS, Leidy. 



CojMPSEmys victus, Leidy, Proceedings Academy Natural Sciences, 

 Philadelphia, 1856, 312. 



Lignite of Long Lake, Nebraska ; Cretaceous of Colorado. 



