13. RHINODONTID^E 31 



numerous, conical, without cusps or serratures ; no nictitating inem- 

 bran?; spiracles very small, above the corners of the mouth; first dorsal 

 large, midway between pectorals and ventrals; second dorsal and anal 

 small; caudal tin lunate, the upper lobe considerably the larger; caudal 

 peduncle keeled; pectorals and veutrals large. A single genus, with 

 probably but one species; the largest of living sharks; inhabiting the 

 northern seas, (.bamnidcv, part, Giiuther, viii, 394; genus SelacJie.) 



29. CETOREHNUS Blainvillc, 1810. 



Baalring Sharks. 



(Selachc Cuvicr.) 



(Blaiuville, Bull. Soc. Pliilom. 1810, p. 169: type Cctorhinus gunncrl Blaiuv. = Squalus 

 maximus L.) 



The characters of the genus are included above. (*>/-"7, whale ; fnvy, 

 a shark (Squat-ilia), from /nvr h a file or rasp, the rough skin of the shark 

 being used for polishing wood and marble.) 



39. C. maximus (L.) Blaiuville. Basking Shark. 



Body rugose, the skin very rough, with small spines ; head small ; 

 snout blunt ; eyes small ; teeth in six or seven rows in each jaw, about 

 200 in each row ; first dorsal large, triangular, over the space between 

 pectorals and veutrals ; second dorsal much smaller, rather larger than 

 anal ; tail large. Largest of the sharks, reaching a length of nearly 

 forty feet ; found in the Arctic seas ; straying southward to Portugal 

 and Virginia. 



(Squalns maximus L. Syst. Nat. : Selachns maximus Storer, Fish. Mass. 229 : Selachc 

 maxima Giinther, viii, 394.) 



FAMILY XIII. RIIINODONTID^E. 



(The Whale Sharks.) 



Origin of the first dorsal fin somewhat in advance of the ventrals ; the 

 second small, opposite to the anal ; both without spines ; a pit at the 

 root of the caudal, with the lower lobe of the caudal well developed ; 

 sides of the tail with a keel ; no nictitating membrane ; spiracles very 

 small ; mouth and nostril near the extremity of the snout ; teeth very 

 small and numerous, conical ; gill-openings wide, the last one above the 

 base of the pectorals. Large sharks, of warm seas. Two species are 

 known, Rhir.odon typicus from the. Cape of Good Hope, and the follow- 

 ing. (Khinodontidce Giinther, viii, 396.) 



* Teeth each recurved backward and acutely pointed, swollen, and with a heel-like 

 projection in front rising from its base MICRISTODUS, 30. 



