64 



THE EXTINCT BATRACHIA, BEPTILIA 



alveolus, and whoue development had occasioned the absorption of half the fang of the functional tooth. Onthe-basis 

 of this tooth 1 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 externa.] face is strongly convex, though not so much so as in T. antiqua. The edges are erenate, but not so as 

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



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

 animal is adult ; their upper portions are lost. The diapophyses have bad 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 to the centrum ; and although the posterior lumbare are always more depressed than the dorsals, 

 yet the present seems too mueh so to have pertained to the same, specie* It differs from tlu.se of T. antiqua also, 

 ;„ ,,,.„, the Hoorofthe 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. 



n. 



Length fragment of mandible, 



Diameter of alveolus, 



Axial width from margin alveolus to symphysis above, 



,1,,. 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, 



Length lumbar vertebra, (centrum), 

 Width cup, 

 Height cup, 



The above estimate of length is based on the proportions of the Gavialis gangcticus as given by Ouvier. 



T 1 1 B ( ! A ( ! 1 1 A MPSA A N T I Q l J A , Leidy up. 



T -i t ior.1 on? i, „,,.,, Ar. isr Sei II 135 Tab. ? Theoaohampsa eontusor, Cope. 

 Crocodtiui anUquus, Leidy. L. o. 1851, 807. Journ. AC. nt. dci., h., j.ou. i 



Proe. A. N. Bci., 18(17, 148. ' 



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

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



the last,, and the teeth will not enter its alveolae. It is probably the largest of the kno-* d Crocodiles oi this country. 



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

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

 and the T. sicaria C. Fig. A reprcsescnts the former and lig. 1? the latter. 



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



and partial destruction of the enamel. 



"Eocene" of Eastern Virginia, from the banks of the Potomac. 



33 



In. 



Lin- 



8 



4. 





11. 



1 



4. 



2 



8. 



3 



3. 





8. 



2 



8. 



09 



5. 



4 





3 



10. 



2 



3. 



2 



0. 



Fig. Hi. 



THECACHA M PSA SERICODON, Cope. 



Proceed. Acad. Nat. Bel., I'l.ila.l., L867, p. 113. 



This 'species was established on fragments of three teeth from the Miocene of Maryland. 



m|| , ;ll , m „, ; perfect teeth, with fragments of .jaws, from New Jersey, presented by my friend, Dr. 11. (,. Wood, Jr. 

 elucidate the characters of both species and genus. 



Four additional and 



