142 



THE EXTINCT BATRACHIA, REPTILIA 



The humerus is curved like tlie femur, but is flatter and broader as compared with the other dimensions. The 

 shank is flattened, and the condyles relatively less dilated transversely than those of the femur. Inside the inner 

 distal margin is a deep open groove, for the passage of the humeral artery. The coracoid has a constricted shall ; 

 its clavicular articular face is short, and the suture smooth. Tn Trionyx, the latter is longer and interlocking. 



Estimated length carapace, 

 Estimated width " 



In. 

 26 



24 



The following characters are observed in the Harrisonville specimen : 



The species differs from the Osteopyges in its relatively wider posterior marginal plate, with very indistinct 

 dermal sutures ; though (tie surface is fully preserved and the vascular grooves distinct, these are very faint. The 

 costal pit is less flattened, and the inner margins of the plate are equal, the upper being less prolonged. The ante- 

 rior marginal differs from the same in 0. emarginatus, in lacking an open groove within the lower margin. The form 

 of the femur has been noticed in the remarks on the genus. It is considerably curved, and with a, slender shaft. 

 The inner condyle is the larger, and within it is a, compressed longitudinal ridge. Surface striate with small ridges. 



Edge of the posterior marginal hone slightly recurved. 



Length eighth marginal, 



Width 



Depth " " at rib pit, 



" hist anter. marginal with rib at margin, 

 Width condyles femur, 

 Diameter shaft, near middle, 



Length phalange, 



'n. 



Liu 



:s 



7.5 



3 



1.5 





li. a 





0.5 



i 



0.7 





8.5 



t 



1 



The Euclastes platyops, Cope, is only known from a cranium found in the same limestone. The present species 

 bears some nearer relation to that in dimensions than any known. 



A very large specimen of this species was presented to tl.e author by John Miers, who procured it from his pit near 

 Ilornerstown, from the upper cretaceous green sand. Its dimensions exceed those of any of the other Chelydrinae, 

 yet they present the incomplete [extension of the union of the marginal and carapacial bones characteristic of the 

 genus. 



Length of ninth marginal 



Width, 



Depth (medially within), 



Length tenth marginal, 



Width, 



In. 



4 

 3 



1 



4 

 4 



Lin. 

 4 

 (i 

 2 

 1 

 1 



These marginals arc opened by 1. 1. c. margiuato at tin; end of the inter-marginal ecutal sutures. The mea are 

 ments of the proximal extremity of the humerus give further indication of its proportions. 



Length of the condyle and deltoid ridge, 

 " " " alone, 



" " postero-interlorerest, 



In. l.in. 



2 i) 



1 4.5 

 1 



