MAETLAND GEOLOGICAL SUKTEY 67 



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

 find, to attrition and partial destruction of the enamel." 



Occurrence. — Calvert Formation. — Charles county near the Patux- 

 ent river. 



Collection. — Formerly in the Philadelphia Academy of Natural 

 Sciences. 



Thecachampsa ( ?) ANTiQUA (Leidy). 

 Plate XXVII, Figs. 7, 8, 9. 



Crocodilus antiquus Leidy, 1851, Proc. Acad. Nat. Sci. Pbila., vol. v, p. 307. 

 Crocodilus antiquus Leidy, 18.53, Jour. Acad. Nat. Sci. Pliila., 3nd ser., voL ii, pp. 



13.5-138, pL xvi, figs. 1-5. 

 Crocodilus antiquus Emmons, 1858, Rept. N. Car. Geol. Survey, p. 215, fig. 35b. 

 Thecachampsa contusor Cope, 1867, Proc. Acad. Nat. Sci. Phila., vol. xix, p. 143. 

 Thecachampsa autiqua Cope, 1869, Proc. Acad. Nat. Sci. Phila., vol. xxi, p. 13. 

 Thecachampsa antiqua Cope, 1869, Trans. Amer. Philos. Soc, vol. xiv, p. 64, fig. 16. 

 Thecachampsa {Crocodilus) antiqua Cope, 1883, Amer. Nat., vol. xvi, p. 983. 

 Crocodylus antiquus Hay, 1903, Bull. 179, U. S. Geol. Survey, p. 513. (In part.) 



Description. — The description given by Leidy is as follows: "One 

 of the teeth, represented in Fig. 1, Plate XVI, is a little less in 

 breadth than the first anterior inferior tooth of the adult Crocodilus 

 hiporcattis. In the specimen the lower part of the fang has been 

 broken away, but the tooth appears to have been as long, or nearly so, 

 as that referred to of C. Hporcatus. It is slightly less curved than that 

 of the latter, and the crown, though as long, is much less robust, more 

 slender, less curved, and more pointed at the summit. The enamel is 

 more finely and sharply striated and at the apex of the crown is not so 

 rugous, and its lateral carinated ridges are not so elevated and extend 

 but a relatively short distance below the point of the tooth; upon one 

 side disappearing entirely nine lines from the commencement, and on 

 the other after five lines only. The fang is simply cylindrical and 

 invested by a thin lamina of osteo-dentine continuous with the basal 

 edge of the enamel. The large conoidal pulp cavity of the tooth 

 extends to within eight lines of the summit of the crown. Within this 

 cavity, in the specimen which was not at all worn off from use, was 

 already formed a young tooth, represented in Fig. 2, closely corre- 

 sponding in form with the half inch of the summit of that which 

 ensheathed it, a circumstance, however, which is the ordinary one in 

 the living species of Crocodile. 



