252 University of California Publications in Geology [Vol- 1 



Carcharodon branneri, while in Carcharodon megalodon Charles- 

 worth from South Carolina we count 100 to 120. This distinc- 

 tion is of very doubtful value, and most likely Leriche is right 

 in referring C. branneri to the synonym of Carcharodon megal- 

 odon, a species recorded from the Tertiary in various parts of 

 the world, and undoubtedly the largest of all sharks. A large 

 specimen of C. branneri in Mr. Morrice's collection agrees fully 

 with C. megalodon from South Carolina. 



17. Carchorodon rectus, Agassiz. 



Miocene of Kern County. 

 This species, if different from Carcharodon megalodon is dis- 

 tinguished by the presence of a lateral denticle. It may be the 

 young of one of the other species mentioned here, although none 

 of these have a lateral denticle. The serrae are about fifty on 

 each side. Probably the upper figure on page 103 of Jordan's 

 memoir represents a lateral tooth of this species. If so, it may 

 be known also by its very coarse serrae. 



18. Carcharodon arnoldi Jordan. 



Pliocene, Pescadero ; Quaternary, Rustic Canon, Santa 

 Monica. 



This species is identified by Leriche with the living species 

 Carcharodon carcharias (L), (Carcharodon rondeletii Muller 

 and Kurle). It has larger teeth than any yet found of the living 

 species, and these are more closely serrated. It is therefore 

 probably distinct. 



19. Carcharodon riversi Jordan. 



Santa Monica, Port Los Angeles, Quaternary ; Miocene of 

 Kern and Fresno Counties. 

 Leriche refers this species also to the living Carcharodon 

 carcharias. This view seems improbable. It is perhaps not 

 distinct from C. arnoldi, and Carcharodon rectus may not be 

 different. In the living species, C. carcharias, the serrations on 

 the teeth do not exceed 35 on each side, those of the middle of 

 the side having most. C. riversi has about 40, C. arnoldi about 

 50, and C. rectus 50 to 60 on each side. C. rectus, as already 



