618 ORDER CHONDROPTERYGII. 



ring which supports this lip results from the union 

 of the palatines and mandibularies. All the bodies 

 of the vertebrae are traversed by a single ten- 

 dinous cord, filled internally with a mucilaginous 

 substance, which undergoes no strangulations, and 

 reduces them to the condition of cartilaginous rings, 

 scarcely distinct one from the other. The annular 

 part, though a little more solid than the rest, is not, 

 however, cartilaginous in its whole circuit. No 

 ordinary ribs are visible, but the little branchial ribs, 

 scarcely sensible in the squali and the rays, are here 

 very much developed, and united to each other, to 

 form as it were a sort of cage, while there are no 

 solid branchial arches. The gills, instead of forming 

 combs, as in most other fishes, present the appearance 

 of pouches, resulting from the union of one of the faces 

 of one gill, with the opposite face of the neighbouring 

 gill. The labyrinth of the ear of these fishes is en- 

 closed in the cranium ; the nostrils are opened by a 

 single hole, in front of which is the orifice of a blind 

 cavity \ 



Their intestinal canal is straight and narrow, with 

 a spiral valve. 



Petromyzon, L. (The Lampreys 2 .) 

 Are recognized by the seven branchial apertures 



This is what authors erroneously name air-hole. See in 

 general on this family, Dumeril, Diss, sur les Poiss. Cyclostomes. 



Lamprey, Lamproie, Lampreda, are names corrupted from 

 Lampelra, which itself is modern, and derived, as some writers 



