NATURAL SCIENCES OF PHILADELPHIA. 11 



Upper edfre broad behind only, and these bearing only the inner series of 

 foramina. Elsewhere with a median ridgre and rows of foramina below on 

 each side ; much decurved ; less convex externally. Medium... E. expanscs. 



Upper edge nowhere broad, and with a deep or shallow groove below it on 

 inside; less decurved, less convex externally ; small E. pcsillus. 



EscHRicHTiDS LEPTOCENTRUS Copc, Procecd. Ac. N. Sci., Phil., 1807, 147. 



The largest of the miocene species, the vertebrae considerably exceeding 

 corresponding ones of the E. c e p h a 1 u s. 



ESCHRICHTR-S CEPHALtJS Cope, loc. cit. p. 148. 



Indicated by a large part of the cranium and other parts of the skeleton, 

 ■with flipper, etc., from Charles Co., Md., and by a portion of the mandible of 

 a second individual from near the mouth of the Patuxent River, Md. 



EscHRiCHTius PRiscus Leidy. Bahenn prison Leidy, Pr. A. N. S. Phil., 1851, 



308. Balirnoptera prisca Cope, 1. c. 1867, 144. 



A portion of a mandibular, ramus of this species furnishes all that we know 

 of it. In size it is intermediate^^between the two here preceding and follow- 

 ing it. 



The miocene of Westmorland Co., Va. 



EsCHRiCHTius EXPANSUS Copc. Meguptera evpansa Cope, 1. c , 1868, 193. 



In addition to numerous vertebrff", portions of the limbs and of three man- 

 dibular rami of two individuals have been discovered. The latter present, for 

 a marked distance on the proximal portion, a flat plane on the upper face, in- 

 stead of the usual argulate ridge, which is equally distinct from the outer 

 and inner faces. In E. p r i s c u s the superior plane is only a continuation of 

 the outer convex face, and accordingly the external series of nutritious fora- 

 mina extends along it. The plane is occupied on the other hand, in the E. e i- 

 p a n s u s, by the inner series. 



The inferior margin is a rather obtuse angle ; the general form is not com- 

 pressed, nor much convex externally, as in E. p r i s c u s. 



Inches. 



Depth ramus 2-75 



Thickness " 1-65 



Foramina (internal) two in 2-.50 



From the mouth of the Patuxent, coll. of P. T. Tyson, State Geological Sur- 

 vey of Maryland. 



EscHRiCHTius PCSILLUS Cope, Procced. Acad. Nat. Sciences, Philada., 1868, 



159, 191. 



A ramus of the mandible of this species from the mouth of the Patuxent 

 River differs from the type in having the inner groove of the superior margin 

 much less marked ; the inner face is plane, but leaves the superior groove 

 "with a marked convexity. The outer face is gently convex, and the outer 

 foramina open externally. Slightly decurved, as well as curved longitudinall3^ 

 Behind the foramina, the superior margin rises to a well marked base for a 

 coronoid process, which is not preserved. 



Inches. Lines. 



Depth ramus 1 io-5 



Thickness 1 2-5 



Foramina (internal) intervals !• 



CROCODILIA. 



THECACHAMPSA Cope. 



Further investigation shows that this genus is gavial-like, and that the 

 peculiarity which characterizes its dentition also belongs to Plerodon Meyer 

 of the European Miocene. Thoracosaurus, of the American Cretaceous, pre- 

 sents also the same character. Plerodon differs from the American form in 



1869.] 



