FISH IN GENERAL. 51 



same manner as in fishes with hard bones, but less abundantly 

 and the texture of the bones does not become quite so hard 

 and homogeneous as in several of the osseous species. Thus 

 for example, in tetrodon mola the bones appear like scattered 

 fibres within membranes. In the lophius piscatorius, or the 

 angler, they are nearly as soft ; but other tetrodons and 

 diodons, balistes and ostracions have more dense bones, and 

 some of them are little less so than in ordinary fishes. Artedi 

 and Linnaeus have refused them opercula and branchiostegous 

 rays against the fact; balistes have even ribs, their only 

 osteological difference arises from the granulations on their 

 jaws; and syngnathi have regular bony jaws, but they want 

 ribs and branchiostegous rays. Most osseous fishes have their 

 bones as hard or harder than other animals ; some are so 

 homogeneous and solid as to show no pores or fibres, and 

 appear to the eye of a vitreous texture. 



Neither osseous nor cartilaginous fishes have either epiphyses 

 on their bones, or medullary canal within them ; but there are 

 some, like the trout, the tissue of whose bones is penetrated 

 by an oily juice ; in others, like the dory, where the internal 

 part of certain bones continues cartilaginous, while the sur- 

 face is completely ossified ; and finally, some, while the rest 

 of the skeleton becomes very hard, retain bones constantly 

 in a state of cartilage, as those of the head of the pike. 



ARTICULATION OF THE BONES OF FISHES. 



The articulations of the bones of fishes display the same 

 variations as in other animals ; but the arthrodiae and 

 ginglymi, that is, the articulations which admit determined 

 motions, either in one or more directions, are less abundant, 

 because their members are not required to execute such a 



E 2 



