AND AVES OF NORTH AMERICA. 



127 





» 



I 



bono is everywhere remarkable for the thickness of its dense layer, and the closeness of the texture of the spongy. 

 The former is one-third the thickness of the sternal and costal hones fractured. 



The scute sutures of the inferior surface are obsolete; those of the dorsal surface are like those of Adocus; i. c, 

 the vertebrals with bracket-shaped lateral borders with the costal proceeding from the point of the bracket. 



The marginal bones vary much in thickness proxiinally; they have two proximal sutures, one side convex, 

 the other concave. Four have a heavy border, round in section; in two of these it is considerably everted: another 

 has a rather thin margin, slightly decurved, with a submarginal groove separating it from the most massive portion 

 The costal bones are strongly convex in their length, indicating an arched carapace. 



Measurement). 



Ilyosternal width, 



" " to origin axillary abutment, 



" length on median suture, 



" thickness near nicsosternal line, 



" " hyposternal " 



ITypostcrnal thickness near poster, suture, 

 Costal, width, 



" thickness vertebral suture, 

 Marginal No. 1 width, 

 " length, 

 " " proximal thickness, 



No. 5 " 



" length, 



" width, 

 " " width dermal scute, 



This animal is therefore a species of considerable size, though loss than most of those described here, and par- 

 ticularly convex and solid in every part. While the sutural lines of the hyosternal measure about the same as in E. 

 firmus (Emys Leidy), it is much more convex and not so thick at the mesosternal suture. The marginal bones are 

 relatively just half the size. The Plonrosternum pec to rale, differs in being very much (latter, and in having a, 

 more discoid mesosternal bone. The hyostemals are also much thicker at their union with the marginals, than the 

 present is. 



A portion of a hyo-or hyposternal bono collected at the same place, and near or at the same time, may ho referred 

 to a larger individual of the same species or to E. firmus. Tt exhibits a wedge for a diagonal gomphosis, between 

 the two sutures, which are preserved. The thickness on the median suture is 14 lines. 



The density of the stomal bones is in marked contrast to that of the E. crassns 

 according to Owen, where the structure is remarkably spongy and open. 



EMYS TTJRGIDUS, Cope. 



This species is represented by two individuals in a mote or less fragmentary condition 

 in the private collection of Dr. Samuel Lockwood, of Keyport, N. J. One of these, 

 selected for description, embraces proximal portions of four lei't costal bones and of three 

 right ones, with a vertebral, other fragments of costals, four marginals (one from the 

 bridge), the greater part of both hyosternals and the mesosternnm. 



These indicate a species of about half the bulk of the E. petrosus, and differing in 

 many particulars. Tbese are especially the relatively much wider and flatter, hyoster- 



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