100 CL;LSSIFICATION OF FISHES. 



feet of birds and quadrupeds, are almost always present ; 

 and. the gill- covers are not only moveable, but the 

 branchial aperture is fully developed — in other words, 

 it does not assume the form of a simple slit or spiracle, 

 as in the eels and rays. Here, then, we find the three 

 chief characters of osseous fishes ; the first absolute, 

 the two next less so : and it may safely be asserted, 

 that every fish which possesses tvro out of these dis- 

 tinctions, finds its natural place in the spiny or the 

 soft-rayed divisions. These we regard, like our prede- 

 cessors, as the two most typical orders of the whole 

 class. We shall now enumerate their characters some- 

 what more in detail. 



(86.) The AcANTHOPTERYGEs have the anterior rays 

 of the dorsal fin simple, rigid, and acute ; the remainder 

 being branched and articulated; or, if there are two dorsals, 

 the first is entirely composed of spinous rays. We are 

 now, as in the following definitions, speaking of the 

 pre-eminently typical examples ; the exceptions will be 

 noticed afterwards. The anal fin is also usually furnished 

 with both sorts of rays, and the membrane is never 

 fleshy. The branchial aperture is large ; the bones of 

 the operculum fully developed, and frequently spinous 

 or serrated ; the eyes large and lateral ; the body ovate 

 or oblong" ; the ventral fins placed near the pectoral ; 

 the scales hard and shining, ornamented with beautiful 

 colours, or richly silvered. They are almost all marine 

 fish, and are more constructed for long continued motion. 

 The aberrant families of this immense order, which in- 

 cludes more than one half of all the fish yet discovered, 

 presents us with several deviations. Some of the blen- 

 nies are viviparous ; and the simple rays of their dorsal 

 fins are sometimes soft ; so also are those of the Ophi- 

 cephali. In the Gymetre^s, the ventral fins are occa- 

 sionally wanting ; but the branchial aperture is large : 

 the fins are fleshy in the blennies, and scaly in the 

 chaetodons. 



(87.) The 3IALAC0PTERTC-ES, or soft-rayed order, is 

 less numerous than the last, and are so much diversified. 



