PROGRESS OF ICHTHYOLOGY. 405 



dropterygians or cartilaginous fish, and that oafish 

 properly so called. 



" The first of these series has for its character, 

 that the palatine bones replace, in it, the bones of 

 the upper jaw : moreover the whole of its structure 

 has evident analogies, which we shall explain. 



" It divides itself into three ORDERS : 



" The CYCLOSTOMES, in which the jaws are 

 soldered (sendees) into an immoveable ring, and the 

 bronchiae are open in numerous holes. 



" The SELACIANS which have the bronchia? like 

 the preceding, but not the jaws. 



" The STURONIANS, in which the bronchia? are 

 open as usual by a slit furnished with an operculum. 



" The second series, or that of ordinary fishes, 

 offers me, in the first place, a primary division, into 

 those of which the maxillary bone and the palatine 

 arch are dovetailed (enarenes) to the skull. Of 

 these I make an order of PECTOGNATHS, divided 

 into two families; the gymnodonts and the sclero- 

 derms. 



"After these I have the fishes with complete 

 jaws, but with bronchia? which, instead of having 

 the form of combs, as in all the others, have the 

 form of a series of little tufts (houppes). Of these I 

 again form an order, which I call LOPHOBRANCHS, 

 which only includes one family. 



"There then remains an innumerable quantity 

 of fishes, to which we can no longer apply any 

 characters except those of the exterior organs of 



