64 THE EXTINCT BATRACHIA, EEPTILIA 



alveolus, and whose development had occasioned the absorption of half the fang of the functional tooth. On the basis 

 of this tooth I am enabled to determine the distinctness of this crocodile from the T. antiqua. The crown, instead of 

 being like that species, a cone with a circular section, with a narrow cutting longitudinal ridge rising abruptly from 

 the surface on each side, in this tooth has a lenticular section, with the cutting ridges on the acute opposite angles. 

 The external face is strongly convex, though not so much so as in T. antiqua. The edges are crenate, but not so as 

 to produce a serration of the margin. Enamel finely obsoletely striate. 



The vertebra preserved is a posterior lumbar. The entire coossification of the neurapophysis indicates that the 

 animal is adult ; their upper portions are lost. The diapophyses have had an oblique basis, rising anteriorly, their 

 middle being opposite the plane of the neural canal, the whole length standing on the anterior two-fifths of the length 

 of the centrum. The cup is subcircular, wider transversely ; the centrum is depressed ; below broad, with a median 

 longitudinal concavity ; sides vertical. As compared with the dorsal vertebra: of T. antiqua, the latter are much 

 more compressed in the centrum ; and although the posterior lumbars are. always more depressed than the dorsals, 

 yet the present seems too much so to have pertained to the same species. It differs from those of T. antiqua also, 

 in that the floor of the neural canal is entirely plane and smooth ; in the latter it is deeply grooved, in consequence of 

 the non-coalescence of the expanded bases of the neurapophyses. 



Ft. 

 Length fragment of mandible, 

 Diameter of alveolus, 

 Axial width from margin alveolus to symphysis above, 



do. do. do. do. below, 



Greatest width to median line (behind), 

 Long diameter crown, at middle of length, 

 Width muzzle, 

 Estimated length cranium, 



do. total length, 33 



Length lumbar vertebra (centrum), 

 Width cup, 

 Height cup, 



The above estimate of length is based on the proportions of the Gavialis gangeticus as given by Cuvier. 



THECACHAMPSA ANTIQUA, Leidy sp. 



Crocodilus aniiquus, Leidy. L. c. 1851, 307. Journ. Ac. N. Sci., II., 135. Tab. ? ' Thecacliampsa contusor, Cope. 

 Proc. A. N. Sci., 1867, 143. 



This species continues as-yet to be represented only by the specimens on which it was based, viz., two teeth, two 

 vertebra;, an ungueal phalange, and a rib. These indicate a large species ; the vertebra} are even larger than that of 

 the last, and the teeth will not enter its alveolae. It is probably the largest of the known Crocodiles of this country. 

 Fig. 16. I have noticed only two dentinal cones in the two teeth we possess. 



The accompanying outlines are those of sections of the teeth of the present species, 

 and the T. sicaria C. Fig. A represesents the former and fig. B the latter. 



The peculiar form of the tooth on which T. contusor was based, is due I find to attrition 

 and partial destruction of the enamel. 

 B A " Eocene " of Eastern Virginia from the banks of the Potomac. 



THECACHAMPSA SEPJCODON, Cope. 

 Proceed. Acad. Nat. Sci., Philad., 1867, p. 143. 



This species was established on fragments of three teeth from the Miocene of Maryland. Four additional and 

 much more perfect teeth, with fragments of jaws, from New Jersey, presented by my friend, Dr. H. C. Wood, Jr., 

 elucidate the characters of both species aud genus. 



In. 



Lin. 



8 



4. 





11. 



1 



4. 



2 



8. 



3 



3. 





8. 



2 



8. 



69 



5. 



4 





3 



10.5 



2 



3.5 



2 



0.8 



