86 CARCHARODON CARCHARIAS. 



the end of the snout, three and one-half inches above the 

 mouth, with an inter-orbicular space of nine inches. The 

 irides are dark brown, and the pupillary openings are 

 large and black. 



NOSTRILS. 



The nostrils are of irregular form, one and one-half 

 inches long and half an inch wide, extending from two 

 and a quarter inches in front of the lower level of the 

 orbits downward and inward. They are not confluent 

 with the mouth, and have a flap-like fold on their exter- 

 nal margin. 



MOUTH AND JAWS. — (PLATE II). 



The mouth is large, inferior, and without labial folds. 

 The jaws, narrower at the inner angle, have the shape of 

 a horse-shoe. The upper jaw is ten inches long on the 

 dental margin, seven and one-half inches wide in front, 

 (at the fourth tooth), and six and one-half inches wide 

 behind at the inner angle. The lower jaw is nine inches 

 long, six and one-half inches wide in front (at the fourth 

 tooth), and Ave and one-half inches wide behind at the 

 last tooth. 



DENTAL FORMULA. 



R 12 or 13 T,13 — 2 5 or 2 6 

 TT • -^ TT — 2 2 • 



The teeth in both jaws have the form of an isosceles 

 triangle, compressed, with the inner surface slightly 

 convex, and the margins rectilinear and markedly ser- 

 rated. They have no basal cusps, and stand a little ob- 

 liquely inward. The upper are larger than the lower 

 teeth, and, in both jaws, the largest teeth are in front. 

 In the upper jaw the front teeth measure seven-eighths 

 of an inch at the base, and one and one-quarter inches 

 on each side, and in the lower jaw live-eighths of an inch 

 at the base, and seven-eighths of an inch on each side. 



