uo 



THE EXTINCT BATRACHIA, REPTILIA 



The accompanying cut is a restoration of the typical species of the genus, and may be 

 compared with those of the genera preceding and following. Like the others, it is derived 

 from a great number of broken fragments which have been arranged and attached. On 

 one side the dermal sutures have been omitted for clearness sake. 



The structure of the sternum appears to be identical with that of Osteopygis. 



Tt may be added that the genus Euclastes, Cope, was established on the cranium of a 

 turtle, which will perhaps be found to enter either this genus or Osteopygis, in either of 

 which cases it will have priority of publication. 



PROPLEURA SOPITA, Leidy, 



CMone topita, Leidy, Cretao. Rept. N. Amor. Smiths, contr. xii., 1.04. Osteopygis «., Cope, Pr. A. N. S., Phila., 

 1808, 147. 



This species is indicated by two marginal bones, part of a costal, half a femur, a tarsal and two phalanges, which 

 lay in close proximity in a block of the Timber creek Limestone taken from the quarry of Barclay Edwards, near 

 Harrisonville, Salem county, N. .1. The original specimen, several marginal bones of one Individual, are in the 

 State Collection of New Jersey, while the specimens also described and figured by Leidy in the Cretaceous Reptiles, 

 I can scarcely refer to the same species. 



The principal evidence, however, on which this species rests, is a partially complete carapace and plastron, with 

 some limb bones from the marl excavations at Birmingham, N. J.; and for which the Academy of Natural Sciences is 

 indebted to Judson Gaskill, one of the proprietors. The portions preserved are the first, third, fourth, seventh to 

 caudal marginal hones of one or both sides; the front vertebral, with numerous costals and the hyo- hypo, and frag- 

 ments of epi- and xiphisternal elements. 



The specimen is of about: the same size as that on which Osteopygis emarginatus, frcm Ihe same place is chiefly 

 based, and the anterior marginal bones are similar in proportions to those of the latter, and not so broad in relation 

 to their length as in 0. platylomus. In some other respects it approaches nearer the otter, which seems to stand 

 rather between it and the 0. emarginatus. 



The front marginals are of about the same length as those of the <). platylomus, but are very much thinner and 

 lighter. The external margin of the first is convex and continuous, with a marked concavity of the nuchal hone. 

 which is slighter in 0. platylomus, and is wanting in 0. emarginatus. The posterior part of the first is of increased 

 thickness, while the second is slid more rapidly heavier. They have no groove on the inner inferior edge, but a wide, 



shallow one externally. This is weak on the third ; the external face of the fourth exhibits a slight contiuuatii f 



it ; the same face of the fifth is regularly concave. The superior face of the seventh is gently concave, and the inferior 

 more strongly convex. The edge of the eighth is slightly everted, while the more posterior areflat. The rib-pitsare 



round conic, those from the ninth posteriorly not completed above, from the thinness of Ihe hones. The edges of the 



posterior bones are not prolonged within that dermal sutural groove. The intermarginal dermal grooves are more 



indistinct in this species than in others, or at least are so in the three specimens I have seen. The COstO-marginal 

 suture is not visible either on the fourth or any more anterior marginal bono. 



Length of edge of nuchal marginal, 

 Length of first marginal. 



Width of " 



Width of fourth " above (greatest) 



Width of " " below (median) 



Length of " 



///, 



J/iii 



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9.6 



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2.5 



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