SHARKS' TEETH AND CETACEAN BONES. 187 



fit Station 13, these latter being quite heavily encrusted, and their sub- 

 stance impregnated with manganese. The most heavily encrusted of all, 

 however, are six large teeth from Station 173 (PI. 2, figs. 31-33), on 

 which the deposit of manganese exceeds 1 cm. in thickness. The largest 

 tooth anywhere obtained is from Station 13, its crown being preserved for 

 a height of 7 cm. 



This species enjoys the same range in the fossil state as Oxi/rhina crassa, 

 but is more cosmopolitan in distribution. In the Tertiaries of the Pacific 

 coast it is known to have extended at least as far north as California, and 

 teeth either of the same or a closely allied species occur in the Patagonian 

 formation of Chubut. 1 A tooth in the Museum of Comparative Zoology 

 from the Tertiary of Aria, Peru, has a total height of 13.5 cm., and a large 

 upper lateral tooth from Coquimbo, Chili, described as C. gigas by Philippi, 2 

 was found in a deposit which has yielded teeth indistinguishable from those 

 of the existing C. rondcletti? The type-specimens of several of Professor 

 Agassiz's species of Carcharodon are now preserved in the Museum of 

 Comparative Zoology. 



CARCHARIIREI. 



Carcharias Cuvikr. 



Plate 1, Figs. 1-6. 



The large family of Requiem Sharks comprises twenty or more recent 

 genera and about sixty recent species, the latter being often closely related 

 and difficult of determination. In many cases the detached teeth of Galeo- 

 cerdo can only be doubtfully separated from those of certain species of 

 Carcharias. The fossil forms having the teeth in both jaws all more or 

 less serrated are usually placed in the subgenus Prionodon (Prionace); those 

 having the upper teeth serrated at the base only, and the lower teeth erect 

 and entire, in the subgenus Hypoprion. The serrated condition of the cor- 



1 Woodward, A. S., Observations on Senor Ameghino's Notes on the Geology and Palaeontology 

 of Argentina, Geol. Mag. [4], Vol. IV. (1S97), p. 22. 



2 Zeitschr. f. gesammt. Naturw., Vol. LI. (1878), p. 0S5, PI. XIX. 



8 Woodward, A. S., On Some Fish-remains from the Parana Formation, Argentine Republic, Ann. 

 Mag. Nat. Hist., ser. 7, Vol. VI. (1900), p. 4. 



