21 



NOTIDANrS. 



CuviER remarks that this genus only differs from the genus Galeus, 

 presently to be described, in not having a first dorsal fin; but even 

 a slight inspection will slicw that the distinction between them is very 

 great; and that Notidanus bears a closer resemblance to Scyllitim and 

 Pristiurus, as well in shape as habits, so far as the latter are known. 

 It even appears that the resemblance is carried so far in a species 

 found in the East Indies, that it is covered M'ith spots, which are 

 black. We place it therefoi'e the next in succession to those its kin- 

 dred genera; and propose to limit it more closely than Baron Cuvier 

 has done, by excluding from it the Mediterranean species with seven 

 gill openings. The shape and general form of the latter will warrant 

 this; but not being an inhabitant of our seas it will not find a place 

 in our History. 



The genus Notidanus therefore, is distinguished by a rounded snout, 

 the want of a first dorsal fin, a lengthened tail, which is stretched 

 out as in the genus Scyllium, an anal fin, and remarkably by the 

 prcspnce of six gill openings. It is the genus Hexanchus of Rafinesque. 



The name Notidanus appears to have been a local one among the 

 Greeks, and may have been applied to the fish we are about to de- 

 scribe. It signifies "dry back," perhaps as being, metaphorically, void 

 of a fin in the usual place. 



Jonston supposes that the term Notidanus may have been applied to 

 quite another species the Centrine, a native of the Mediterranean, 

 but not found with us. 



SIX-GILLED SHARK. 



SIX-BRANCHIAL SHARK. GREY SHARK. 



Squalus griseus, Tueton's Linnaeus. 



Le Squale Griset, Lacepede. Risso; Ichthyologie, p 37 



Grey Shark, Zoologist, 1846, p. 1337. 



Hexanchus griseus. Dr. Gray; Catalogue Br. Mus., p. 67. 



Yaeeell's Br F., 2nd. Suppl., p. 25. 

 Notidanus griseus, Cuvier. 



The example from which the description is taken, measured 

 in length no more than two feet two inches and half; but it 

 has been caught of the length of eleven or twelve feet. The 



