CHAPTER XIX. 
OSSEI, OE BONY FISHES. 
Undee this denomination is comprehended many of the fishes which 
are most familiar to ns. They are characterised, as we have said else- 
where, as a group of animals having a solid skeleton. They are 
divided into six orders ; founded, however, it is necessary to add, on 
characteristics of little organic importance, and the names bestowed 
upon them are of a most barbarous description. These names are, 
I. Pledognathi, namely, fishes in which the upper jaw is attached to 
the cranium, from tr Xetcrbs, interlaced, and 7 vados, jaw. 
Afterwards those in which the upper jaw is movable, and the gills 
arranged in circles, like rounded hoops. These are, II. the Loplio- 
branchii, from Xdc^o?, crested, or aigrette, fipay^ia, gill. 
In the other orders the gills are arranged in a comb-like form. 
These are divided into two great groups. In the first, the rays of the 
fins are soft, except occasionally the first of dorsal or pectoral fins. 
These are, III. the Malacopterygians, from paXa/cos, soft, and 
Trrepv'yi.ov, fins — the third group of osseous fishes. In a later 
group the fish have bony rays to the anterior dorsal fins, some 
osseous rays, and the anal fin and generally one of the ventral fins. 
These are, IV. the Acanthopterygians, from a/cavda, spiny, and 
wrg pvyiov, finned, which form the last group of bony fishes. 
I. Plectognathi. 
Prom their organization the fishes of this order establish the passage 
from cartilaginous to the osseous fishes. Their skeleton, which remains 
