150 THE WASATCH AND BRIDGER FAUNiB. 



MeasttremenU, 



M. 



Length of carapace (axial) 450 



Wiilth of canipaco (axial) 240 



Length of i)lasl ron 290 



Length of anterior lobe 082 



Length of posterior 085 



Width of extremity of anterior lobo 038 



Width of extremity of posterior lobe 057 



Length of nuchal sent a 030 



Length of tliinl marginal 023 



Width of thiril marginal 020 



Width of fonrih marginal 024 



Length of fonrth marginal 028 



Length of right h marginal 030 



Width of .-ighth marginal 035 



This species differs in many details from the preceding species, notably 

 in the forai of the marginals The anterior are wider than in either species, 

 while the median are narrow as in B. undata. The sculpture is very distinct 

 from that of either. 



From the bad lands of Ham's Fork, Wyoming. 



Baena ponderosa Cope. 



Annual Report U. S. Geological Survey of the Territories, 1872 (1873), p. 624. 

 Plate XVIII, figs. 3-8. 



Established on numerous fragments of a specimen of a species which 

 I cannot refer to this genus with certainty, but which agrees with the species 

 already known in some particulars of structure. Thus, the last marginal 

 plates were separated by an excavation of the posterior border; at least this 

 is the only position to which I can refer a portion of the margin of the cara- 

 pace where the marginal scutes suddenly cease. The lateral ribs of the 

 bridge are received into a deep pit between two costals. 



The marginal and other bones are very massive, much more so than 

 in any other known water tortoise of this formation ; the margins of the 

 former are thickened, especially at the last marginal scute, which is on a 

 massive protuberance. The sutures are entirely regular. The lateral 

 marginal scuta are about as long as broad. The surface of the shell is 

 marked with irregular impressions, which are sometimes like rain-drop pits. 

 A posterior vertebral bone possesses a median rib similar to that in Dernia- 

 temys vijomingensis. 



