21 
NOTIDANUS. 
Cuvier remarks that this genus only differs from the genus Gahus, 
presently to bo described, in not having a first dorsal fin; but even 
a slight inspection will shew that the distinction between them is very 
great; and that Notidanus bears a closer resemblance to Bcylliwm and 
Prutmrus, 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 with spots, which are 
black. We place it therefore the next in succession to those its kin- 
dred genera; and propose to limit it moro cIo.sely 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 
tills; 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 Sci/llium, an anal fin, and remarkably by the 
presence of six gill openings. It is the genus HexancMs of llafinesque. 
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 Centring, a native of the Mediterranean, 
but not found with us. 
SIX-GILLED SHARK. 
SIX-BRANCHIAL SHARK. GREY SHARK. 
Squalus griseus, 
Le Squale Oriset, 
Grey Sharlc, 
Hexanchus griseus, 
it fi 
Notidanus griseus, 
Turton’s Linnaius. 
Lacepede. Risso; lohthyologie, p. 37 
Zoologist, 1816, p. 1337. 
Dr. Ga.AY; Catalogue Br. Mus., p. 67. 
Tarbell’s Br P., 2nd. Suppl., p. 25. 
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 
