3S)<) HIIlNObONTlD.K. 



Fam 3. RIIINODONTIDiE. 



Characters of the single genus. 



18. EHINODON. 

 lihiuodon, Smith. 



The oiigin of the first 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. 26; Miill. <5- Heiile, p. 77, tab. 36. 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 Hues. 



Cape of Good Hope ; Seychelles. 



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

 Wright. 



Mr. Gill(Proc. Ac. Nat. Sc. Philad. 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 punctatus. He de- 

 scribes it in the fdUowing terms : — " The dried dentigerous band of 

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

 the extremities, and somewhat more than an inch in width in front. 

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

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

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

 verse row.s, of which there arc 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 acutelj^ pointed, swollen and with 

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



* A pre))aration brought home by Prof. Wright shows clearly that there is 

 really no nictiUitiug membrane. 



