126 



THE EXTINCT BATRACHIA, REPTILIA 



EMYS FIRMUS, Leidy. 



Cretac. Kept. 100, Smithsonian Contrib., No. 192, Adocus firrnui Copo, Proceed. Acad. Nat. Sci., Pliil., 1808, 235, 

 Geolog. Surv. N. Jersey, App. C. 



An individual of tins species is represented by same characteristic fragments in the Museum of Rutger's College, 

 N. J. As remarked, they have many characters like the following species; while in the surface markings, dermal 

 scutes, etc., they resemble as much the Adocus beatus. I have not seen the costal bones. 



This is a large species and of extraordinarily massive construction. This was no 



doubt an adaptation in defense of enemies, perhaps as protection from blows or snaps of 



the more gigantic reptiles of that time. I give the measurement of this species from 



] joidy. 



In. 



Length margin 7th and eighth marginals, 5.75 



Width seventh plate, 2.5 



eighth " 2.75 



Depth " 3.75 



Left hyosternal, length from exterior angle mesostcrnum , 3. 



Thickness at latter suture, 1.+ 



" postcro-medially, .625 



This species is distinguished from hoth the following by the relatively much larger 

 size; of the postero-median, and probably the other marginal bones. Its points of resem- 

 blance to the E. turgidus are more numerous than to the E, petrosus. like both of 

 these the mesostcrnum is truncate behind. 



Position. The upper bed of Cretaceous Green Sand, New Jersey. 



EMYS PETROSUS, Cope. 

 Adocus pgtrofUS, Cope, Proc. Acad. Nat. Sci., Phila., 1808, 230, Geol. Surv. N. Jersey, App. C. 



This species is represented by portions of four costal bones, parts or wholes of six marginal bones, most of the 

 right hyosternal, and a posterior portion of the right byposternal, with the bead of the os coraoo'ideum. They were 

 found in the West Jersey Marl Company's pits, Gloucester Co., N. J., in the same locality whence the Laelaps was 

 procured. It is characterized by the very massive structure of its carapace and plastron, and for the posteriorly 

 truncate form of its mesosternum. Another species (K. Annus) which unites the same peculiarities, is included in 

 this genus, though I have not seen its costal bones. 



The hyosternal bone is preserved in its axillary margin, and is continuous with two marginals of the carapace 

 of the same side. Two of the costals are adjacent and give the outlines of the vertebral bones and scutes. These 

 show the inferior outline to be very convex, the whole, from angle to angle of the marginal bones of opposite 

 sides amounting to an arc of about 124 degrees. Each hyosternal is slightly concave below the plane of 

 their common suture. Each thins out laterally, though the one preserved is very thick on the axillary margin. 

 There is little difference between the thickness at the mesosternal and the byposternal sutures. All the sutures 

 have minute rugosities, differing much from stcrnals in Adocus and Taphrosphys, which arc very ragged, and 

 resembling those of Pleurosternum pectorale m. The piece of byposternal is even thicker than the hyosternal. The 



