TEXTURE OF FISH BONES. 51 



piscatorius, they are nearly as soft. The other 

 Tetradons and Diodons, the Balistes and Ostracions, 

 have denser bones ; and in some species these parts 

 can scarcely be distinguished from those of the 

 osseous fishes. It is certain, also, that the bony 

 frame-work of the fibro- cartilaginous kinds is con- 

 structed on the same plan as that of the truly osse- 

 ous species, and not in accordance, with those of 

 the Chondropterygii ; and it is in opposition to the 

 known truth of nature that both Artedi and Lin- 

 naeus have denied them the possession of opercula 

 and branchiostegous rays. The Balistes have even 

 ribs, their only osteological difference consisting 

 in the granulation of their jaws ; while the Syngnathi 

 have regular bony jaws, although they want the 

 ribs and branchiostegous rays. 



The majority of osseous fishes have bones fully 

 harder than those of other animals, and it is quite 

 a gratuitous assumption to suppose that the observed 

 longevity of certain species arises from the softer 

 consistence of those parts. Certain fish bones, in 

 fact, exhibit neither pores nor fibres, and appear 

 almost vitreous to the eye. But neither the osseous 

 nor the cartilaginous kinds have either epiphyses to 

 the bones, or medullary canal within them; al- 

 though there are some, such as the trouts, in which 

 the tissue of the bones is more or less penetrated 

 by an oily juice ; while in others, such as the dory, 

 the internal portion continues cartilaginous, while 

 the surface is completely ossified. Finally, in cer-' 

 tain species, while the general skeleton is very hard, 



