SHARKS' TEETH AND CETACEAN BONES. ]85 



the exception of Oxi/rhim crassa and Carcharodon majalodon, therefore, the 

 specific determinations must be regnrded as more or less provisional. It is 

 interesting to note that the last two species became extinct in the Pliocene. 



Oxyrhina Agassiz. 



Oxyrhina crassa AoASSiz. 

 Plate 1, Figs. ll-'20. 



Over one hundred specimens of Oxyrhina teeth were obtained at Sta- 

 tion 2, and about lialf that number from Station 13, which may be referred 

 with little hesitancy to this species. Anterior and lateral teeth are repre- 

 sented in about equal proportions, the former signalizing themselves by 

 their high and narrow crowns, not unlike those of the existing 0. simllanzani, 

 and the postero-lateral teeth only differing from those of 0. hastalis in their 

 considerable thickness. The outer coronal face is flat, the inner strongly 

 convex, and the enamel smooth on both faces. The lower lateral teeth are 

 triangular and erect ; in those referable to the upper jaw the apex is some- 

 times lightl}'^ reflexed, and the crown often curved backward. All the teeth 

 from Station 2 exhibit but a slight coating of manganese. The largest- 

 sized anterior and lateral teeth which have been obtained of this species 

 are shown in Figs. 13 and 19 respectively One nearly perfect crown, 

 much perforated by sponge borings, was obtained at Station 17, and a 

 fragmentary one at Station 183, both belonging to this species. 



This species has not been recognized as such by the authors of the 

 "Challenger" Reports, but unnamed Oxyrhina teeth evidently identical 

 with those here described are illustrated in PI. VL, figs. 8-11, 13-17, and 22. 

 Of these only the ones shown in Figs. 14-16 are anterior teeth. Although 

 numerous specimens of 0. linstalis were dredged by the " Challenger," the 

 '•Albatross " Expedition w.as not fortunate enough to obtain .any. 



Oxyrhina crassa ranges from the Eocene to the Pliocene in Europe, and 

 is of rare occurrence in the Pliosphate Beds of South Carolina. The latter 

 deposits, however, contain such an agglomeration of early and late Tertiary 

 fossils that the age of the formation is indeterminate. No good figures of 

 this species having been published heretofore from American localities, two 

 perfect examples are shown in tlie accompanying text-figures, with which 



