348 NEW-YORK FAUNA. 



ORDER II. PLAGIOSTOMI. 



Gills fixed by their external edges, with five small external openings on each side. No 

 opercle. Jaivs represented hi/ the palatine and postmandihulary bones, ivhich alone are 

 armed ivith teeth. Pectorals and vcntrals always present ; the latter {in the male) fur- 

 nished on their internal margins tvith long appendages. 



FAMILY SQUALID.^. 



Body elongated, cylindrical. Tail thick and innscular. Eyes lateral. Branchial openings 

 on each side, never underneath. 



Obs. About eighty species have been described, belonging to this family. 



GENUS CARCHARIAS. Cuvier. 



Snout depressed; the nostrils beneath the yniddlc. Teeth cutting, pointed, and generally 

 denticulated at the sides. First dorsal far in advance of the ventrals ; the second nearly 

 opposite to the anal, which is always present. No temporal orifices ; the last of the bran- 

 chial openings above or slightly in front of the pectorals. 



THE THRESHER SHARK. 



Carcharias vulpes. 



PLATE LXI. FIG. 199. Female. — (AMERIC.\N MUSEUM.) 



Long-taited Shark. Pennant, Br. Zoology. 



Thresher. MiTCHiLL, Medical Repository, Vol. 8, p. 77, figure. (Male.) 



Sqnalus vu^jies, Thresher or Lmig-tailed Shark. Id. Lit. and Phil. Soc. Vol. 1, p. 482. 



Carcharias vulpes. CuviER, Rdgne Animal, Vol. 2. 



C. i(/., Fox Shark, Thresher. Stoker, Report on the Fishes of Massachusetts. 



Characteristics. Upper lobe of the tail nearly as long or longer than tlic body. Length 

 twelve to fifteen feet. 



Description. Body cylindrical, thickest before the dorsal fin, witli a ridge on its upper sur- 

 face towards the tail, and a deep cavity at the base of the caudal fin, as if strangulated. 

 Back regularly arched from above the pectorals to the end of the snout, which is blunt. Skin 

 roughened with minute prickles, which are directed backward, and obvious to the touch. 

 Nostrils small and valvular. Mouth in the shape of a horseshoe, with tluree series of distant, 

 flat, triangular, smooth-edged teeth in each jaw ; the teeth appear to be loosely inserted in the 



