FISHES. 269 



in their texture, their number and length, as in the Barbels, 

 Silures, and the Pogonias. 



Some fishes have thick fleshy cirri on the body as the Scorpoenas ; 

 some of the rays can be detached from the fin, and are capable of 

 independent motion, whether they belong to the vertical fins as in the 

 genus Lophius, or to the pectoral fins as in the Gurnards. 



In fine, the nature of the integuments, whether we speak of those 

 of the body, or of the head, or the fins, is subject to variety ; a fish 

 may be either naked, scaly, spinous, or mailed, in all or only in some 

 of its parts ; its scales, or the pieces of its coat of mail, differ very con- 

 siderably in size, in outline, in the indentations of their borders, and 

 the inequalities of their surface. The same may be said of the various 

 pieces which cover the head. The line, formed on each side of the 

 body by a series of pores or minute tubes excavated in the scales, are 

 sometimes more or less marked, or even mailed and protected ; again, 

 it is more or less straight, or more or less brought nearer the back. If 

 we combine, with all these considerations, what belongs to the colours, 

 the distribution of those colours and their shadings, and further, what 

 belongs to the size and weight of fish, we shall be able to form some 

 idea of the character which distinguishes, externally, the various be- 

 ings of this great class. We shall, at the same time, be struck with 

 the inadequacy of ordinary language to express and convey a just im- 

 pression of all these diversities. 



CHAPTER III. 



OSTEOLOGY OF FISHES. 



After the above general exposition, we proceed to the examination 

 of the various organs, and we shall begin with those which are the 

 support of all the others, namely, those composing the skeleton ; but 

 before we take up the several bones, it is necessary that we should 

 have some previous knowledge of their peculiar nature and their inti- 

 mate tissue. 



Tissue of the Bones in Fishes 



AVith respect to the tissue of their bones, fishes may be divided into 

 the Osseous, Fibro-cartilaginous and True Cartilaginous fishes. 



The last of the divisions, also denominated in former times Chon- 

 dropterygians, and which from their frame- work, their branchiae, (the 

 external edge of which, on each side is, attached to the skin, and 

 through which the water escapes only by means of very small but 

 numerous orifices,) and on account of manyother peculiarities of their 

 organization, are distinguished, very strikingly, from all other fishes, 

 — the fishes of this division, we say being not furnished with true bones. 

 The hard parts of their frame consist internally only of cartilage which 

 is homogeneous and semi-transparent, which is developed on the sur- 

 face of the Rays and Dog-fishes only, in a layer of minute, opaque, and 



