39(i KIIINODONTIDJ;. 



Fam 3. RHINODONTIDtE. 



Characters of the single genus. 



18. EHINODON. 

 Rhinodon, Smith. 



The origin of the tirst dorsal fin is somewhat in advance of the root 

 of the ventrals ; the second small, opposite to the anal ; both with- 

 out spines. A pit at the root of the caudal, which has the lower lobe 

 well developed. Side of the tail with a keel. Membrana nictitans 

 none*. Spiracles very small. Mouth and nostril near the extremity 

 of the snout. Teeth extremely small and numerous, conical. Gill- 

 openings wide. 



Cape of Good Hope ; Seychelles. 



1. Rhinodon typicus. 



Smith, III. Zool. S. Afr. Fish. pi. 20; Miill. ^- Henle, p. 77, tab. 35. fig. 2 

 (teeth) ; Dumeril, Elasmobr. p. 428. 



Snout very broad, short, and flat. Eyes very small. Upper jaw 

 with a long labial fold. Brownish, with whitish dots and narrow 

 transverse lines. 



Cape of Good Hope ; Seychelles. 



a. Portions of the jaws. Seychelles. Presented by Prof. E. P. 



Wright. 



Mr. Gill (Proc. Ac. Nat. Sc. PhUad. 1865, p. 177) has distinguished 

 a large Shark from California, the existence of which is known from 

 the teeth only, under the name of Micristodus pumtatus. He de- 

 scribes it in the following terms : — " The dried deutigerous band of 

 the upper jaw is slightly curved forwards, about 19 inches between 

 the extremities, and somewhat more than an inch in -width in fi-ont. 

 The teeth are fixed and extremely minute, the largest being little 

 more than a line in length (in an example 20 feet long), and decrease 

 towards the ends of the jaw ; they are disposed in regularly trans- 

 verse rows, of w^hich there are over 160 (164—167) on each side, 

 while in front there are from 13 to 16 in each transverse row ; each 

 tooth is recurved backwards and acutely pointed, swollen and with 

 a heel-like projection in front rising from its base." 



* A preparation brought home by Prof. Wright shows clearly that there is 

 really no nictitating membrane. 



