86 SYSTEMATIC PALEONTOLOGY 



by Louis Agassiz ' from the Tertiary of California, and ascribed by him 

 to the upper and lower jaws of one and the same species. As far as 

 can be determined from the published figures, this association does not 

 appear to be justified, and the evidence of Carcharias egertoni and 

 C. collata would go to show that two distinct species are represented. 

 If such a division were to be made, the form with serrated edges shown 

 in Agassiz's Plate I, Fig. 15, should be selected as the type of C. 

 (Prionodon) antiquus, while the others with sharp narrow crowns like 

 that shown in Fig. 16 of the same plate should be transferred to C. 

 collata, which they closely resemble, or else should receive a new specific 

 name. 



Occurrence. — Choptank Formation. Jones Wharf, Dover Bridge. 

 Calvert Formation. Charles county near the Patuxent river. Plum 

 Point, Fairhaven, Chesapeake Beach. 



Collections.— Maryland Geological Survey, Philadelphia Academy of 

 Natural Sciences. 



Carcharias magna (Cope). 

 Plate XXXII, Figs. 6a, 6b, 7a, 7b. 



Sphyrna magna Cope, 1867, Proc. Acad. Nat. Sci. Phila., vol. xix, p. 143. 

 Sphyrna magna Hay, 1902, Bull. 179, U. S. Geol. Survey, p. 314. 



Description. — Teeth of comparatively large size, attaining a total 

 height of nearly 2 cm., and distinguished from C. collata by their wider, 

 Oxyrhina-like crown and shorter root. Coronal edges sharp, non-ser- 

 rated, or only slightly crimped at the base; enamel at base of crown 

 much extended laterally over the root, which is short and considerably 

 thickened on the inner face. 



This species is established on three somewhat dissimilar teeth from 

 the Miocene of Charles county, which are remarkable for their large 

 size as compared with other species of Carcharias and Sphyrna. Owing 

 to the width of the cro"WTi and the extension of its basal portion over 

 the root, a certain resemblance to the teeth of Oxyrhina is to be noted, 

 but the nearest affinities are evidently with the foregoing species. As 



>Rept. Pac. R. R. Explor. and Surv., vol. v (18.56), p. .314, pi. i, figs. 1.5, 16. 



