ELASMOBRANCHII. 75 



midway between pectoral axils and ventrals. Second dorsal 

 much smaller than first, usually not larger than anal. 



Large, slender, swift, voracious sharks in warm seas, compris- 

 ing about two existing and 27 extinct species. 



Glyphis Egertoni (Agassiz). 



Galeocerdo egertonii Cope, Proc. Amer. Philos. Soc. Phila., XIV, 1875, p. 



362. (Cumberland Co. Miocene.) 

 Glyphis subulata Gibbes, Journ. Acad. Nat. Sci. Phila., (2) I, August, 1849, 



p. 194, PI. 25, figs. 86-87. (New Jersey Greensand, from Wetherill.) 



Teeth broadly triangular, well compressed. Crown com- 

 pressed, erect or moderately inclined, and notched on each mar- 

 gin, though posterior or external most conspicuous. Surfaces 

 smooth, convex on inner and outer flattened, latter sometimes 

 with a few vertical basal folds or wrinkles. Cutting-edges finely 

 and conspicuously serrated, the serratures usually extending to 

 the apex. Apex pointed, sometimes deflected. No basal cusps. 

 Root compressed, outer surface depressed or concave and inner 

 moderately convex. Ends of root widely divergent, and lower 

 margin usually emarginate. Length about 17 mm. in larger. 



The lower teeth are said to be probably narrower than the 

 upper. The specimens I have listed all appear to belong to this 

 species, though the differences between Aprionodon gibbesii, 

 Sphyrna prisca and Glyphis egertoni are scarcely evident in some 

 cases. The latter may, to some extent, be characterized by its 

 broad upper teeth. 



Formation and locality. The following teeth are probably 

 from the upper Cretaceous or Miocene beds [the Navesink-Hor- 

 nerstown bed marl, the Manasquan marl, the Kirkwood forma- 

 tions, K.], though no such information is given on any of the 

 labels. Monmouth County 2 without donor, 2 (P. D. Knies- 

 kern), 26 (Knieskern, W. Cleburne, C. C. Abbott) ; Burlington 

 County 13 CT. A. Conrad) ; Vincentown 15 (T. M. Bryan) ; 

 Mullica Hill in Gloucester County 3 (Abbott) ; Allowaystown 

 in Salem County 48 (H. C. Yarrow). 



The following teeth in the collection of the Geological Survey 

 are probably this species: Monmouth County 1 (Knieskern), 2 



