G24 GEOLOGICAL SUEVEY OF THE TERRITORIES. 



M. 



Width of extremity posterior lobe 0.')7 



Length of miclial scuta 030 



Length of third margiuul 0-J3 



AVidlh of tliird marginal O'cO 



Width of fourth marginal O'U 



Length of fourth marginal O^S 



Length of eighth marginal O.'iO 



Width of eighth marginal 035 



This species tliffers in many details from the preceding species, nota- 

 bly in the form ot the marginals. The anterior are wider than in either 

 species, while the median are narrow as in C. undatum. The sculpture 

 is very distinct from that of either. 



From the Bad Lauds of Ham's Fork, Wyoming. 



Baena ponderosa, Cope, sp. nov. 



Established on numerous fragments of a specimen of a species which 

 I cannot refer to this geuus 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})ace 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 w\ater- 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 Djarked with irregular impressions, which are souietimes like 

 rain-drop pits. A posterior vertebral bone possesses a median rib simi- 

 lar to that in •Dermatcmys vyomingensis. 



Measurements. 



M. 



Length of an anterior marginal scute 045 



Width of an anterior marginal scute 0o9 



Thickness of bone at anterior marginal scute 0"2:i 



Length of a free marginal bone 050 



Width of a free marginal bone 057 



Length of first marginal of bridge 0&) 



Thickness at simple end OxJci 



From the Bad Lands of Ham's Fork, Wyoming. 



JDERMATEMYS, Gray. 



liapteviys, Lchlij, Joe. cit. 

 This genus is similar to Emys in the structure of the carapace and 

 plastron, except that the lobes of the latter are narrower and shorter. 

 The scuta are similar, excepting that there is a series of intermargiuals 

 on the bridge on each side. There are thirteen marginals on each side, 

 those of the last pair in contact throughout. In a specimen of the only 

 species known, I find a trace of an intergular scute as is sometimes seen 

 in i>. berardii, now living in Mexico. 



Dermatemys WY^oivnNGENSis, Leidy. 



Loc. cit. 

 From various localities. 



