ELASMOBRANCHII. 61 



greensand 115 (Bryan); Mullica Hill in Gloucester County 1 

 (Abbott) ; Cumberland County 1 (T. B. Gillette). The follow- 

 ing labeled simply "New Jersey" are: 1 (Coates), 1 

 (Budd), 1 (Wetherill), 2 (Chaloner), 3 (Abbott), 1 (W.' Cle- 

 burne), 4 without donor. 



In the Geological Survey collection are the following teeth: 

 Monmouth County 6 (Knieskern) ; Shiloh 9 (E. Davis) ; Vin- 

 centown Cretaceous 2 (Dr. Brown), and 3 without data. [The 

 formations apparently represented are the Navesink-Horners- 

 town bed, the Manasquan marl, Shark River marl and the Shiloh 

 marl, i. e., Cretaceous, Eocene, Miocene beds, K.] 



Carcharodon polygurus (Morton). 



Squalus sp. Morton, Synop. Org. Rem. Cret. U. S., 1834, p. 31, PI. 12, fig. 2. 

 "Found in both the arenaceous and calcareous strata" [the former evi- 

 dently with reference to New Jersey}. 



Carcharias polygurus (Agassiz) Morton, Am. Journ. Sci. Art., XXVIII, 

 1835, p. 277 (name only, based on preceding). 



Carcharodon megalodon Cope, Proc. Am. Philos. Soc. Phila., XIV, 1875, 

 p. 362. (Cumberland Co. Miocene.) 



Teeth comparatively broad, compressed and not especially 

 thick. Coronal surface moderately convex, outer somewhat flat- 

 tened. Apex slightly deflected to one side. Cutting-edges ser- 

 rated, more distinct mostly in smaller examples, and then small. 

 Xo basal cusps. Tips of serratures rounded. Root compressed, 

 outer face flattened, and inner face rather evenly though usually 

 moderately convex. In profile lower margin of root forms emar- 

 gination often at an obtuse angle, or moderately crescentic. Ends 

 of roots usually compressed and about as broad as rest of basal 

 portion. Teeth range from 40 to 133 mm. in length. 



This species seems to be known only from the large detached 

 teeth. These are often with their edges so worn that the mar- 

 ginal serrae appear obsolete or in some cases to be absent. Prob- 

 ably the largest of all fishes, it having been estimated to have 

 reached a length of over twice that of the largest known existing 

 fish, Cetorhinus< maximus, or nearly three times that of its 

 nearest existing relative, Carcharodon carcharias. Bowerbank 

 estimated the length of Carcharodon megalodon to be about 87 



