GEOLOGICAL SURVEY OF THE TERRITORIES. G27 



represent different species, wliicb were stated to differ in tlie form of 

 the episternal bone. This difference app"ears with farther observation 

 to be less important than was supposed. 



This species is known by portions of several speciniens. The type is 

 liirger than any of the last described, and equaled some of the Cldoni- 

 i(hv of the ocean in dimensions. The right hyosternal bone indicates 

 both resemblance and difference from the iV. testudmen. The former is 

 seen in the internal tliickening- parallel to the margin, bounded behind 

 by a deep groove extending; to the axilla. A peculiarity, in which it 

 differs from the N'. testudinea, is seen in the posterior position of the 

 humero-pectoral dermal suture, which originates at the axilla. The 

 epihyosternal suture is concave. The thickened portion of the epister- 

 nal margin is shorter and wider than in the si)ecies just named, the 

 width being to the length as 2.5 to 2 : in X testudinea, as 1.5 to 2. 



Measurements. 



M. 



Thickness of hyosternal anteriorly Oil 



Width of costal, (?) second specimen Ood 



Surfaces not sculptured. 



From Green River strata, near Evanston, Wyoming. 



Emys testudineus, Cope. 



Nofomoiyha testudinea, Cope, Joe. cit., p. 475. 



Represented by portions of four or more individuals. In' one of these 

 the anterior lobe of the plastron is in part preserved. The mesosternum 

 is a transverse oval, the posterior margin regularly convex, the anterior 

 with three equal borders. The median of these is concave. The sutures 

 are radiating, and the groove separating the humeral scuta appears to 

 traverse the entire length of the bone. The outer surface is gently con- 

 vex. The free margin of the episternal and hyposternal bones is acute, 

 and with an interiial thickening, as in Cistndo, Testudo, &c., forming a 

 ridge, with abrupt inner face. This face extends backward as a groove 

 to the axillary process of the hyosternal, forming a characteristic mark. 

 Although the extremity of the episternal bone is lost, and the meso- 

 sterual exhibits no trace of the intergular scute, the outer sutures of the 

 gular scuta are so far posterior as to render it highly probable that the 

 intergular plate existed. At the point where this suture reaches the 

 margin the latter is openly emargiuate. The posterior suture of the 

 humeral scute crosses the iuargin halfway between the axilla and the 

 episternal suture, and is not marked by a notch. The last-named suture 

 is transverse. On the xiphisternal bones the groove of the anterior 

 suture of the anals is plainly visible. It is regularly convex forward, 

 and in one specimen is double. 



In a second specimen of about the same size parts of two costal bones 

 are preserved. They arc thick, and display the usual costal and verte- 

 bral scute-sutures, ithe latter one in a groove, for the middle of the 

 vertebrals is elevated, and the costals project shoulder-like just outside 

 the groove. 



In a third specimen, a little larger, xiphisternals with several margi- 

 nals are preserved. A free posterior marginal is rcgulaily recurved, 

 and the scute-sutures are deeply impressed. The marginal scuta have 

 evidently been marked with concentric grooves within their margins. 

 Tlie first marginal ])one of the bridge has a very obtuse edge. 



In none of the specimens are the surfaces sculptured. 



