FlXED-GILLED CHONDROPTERYGIANS. 241 



vulg., King of the Herrings ; the Chat of the Mediterranean. 

 (The Arctic Chimsera.) Two or three feet long, of a silvery 

 colour, and spotted with brown. It inhabitants our seas, and it 

 is caught generally in the wake of the Herrings. In the 



• Callorhynchus, Gronov. 



The snout is terminated by a fleshy appendange resembling a hoe 

 as to form. The second dorsal commences over the ventrals and 

 terminates opposite the beginniug of the fin attached to the under 

 part of the tail. But one species is known. 



Chim. callorhynch., L. ; Lacep. I, xii, a female. (The Antarc- 

 tic Chimsera.) From the South Seas. 



ORDER II. 



The Second Order of Cbondropterygians or the Eighth of Fishes 

 is that of the 



FIXED GILLED CHONDROPTERYGIANS. 



Which, instead of having those organs free on the external edge, 

 and opening all their intervals into a large common orifice, as is 

 the case in all the fishes of which we have hitherto spoken, have them 

 adhering by this external edge in such a manner that they permit 

 the water to escape through as many holes pierced in the skin as there 

 are intervals between them, or. at least, that these holes may termi- 

 nate in a common duct, through which the water is transmitted out. 

 Another circumstance peculiar to these fishes is the presence of little 

 cartilaginous arches, frequently suspended in the muscles opposite to 

 the external edges of the branchiae, and which may be termed 

 branchial ribs. 



FAMILY I. 



SELACHII,— PLAGIOSTOiMI, Dumer. 



This family, hitherto comprised under two genera. Squalus and 

 Raia, has many common characters. The palatines and post-man - 

 dibularies. alone armed with teeth, supply the place of jaws, the usual 

 bones of which are reduced to mere vestiges; one single bone 

 suspends these apparent jaws to the cranium, representing at once 

 the tympanal, jugal and temporal bones, and the prcoperculum. 

 The hyoid bone is attached to the single pedicle just mentioned, and 

 supports branchiostegal rays, as in ordinary fishes, although they are 

 not so very visible, externally; it is followed by the branchial arches, 

 as usual, but neither of the three pieces compose the operculum, 



VOL. II. R 



