308 KISHES. 



pelvis. We rarely find the-first ray of the pectoral ramified, and its 

 joints are sometimes so soldered together, as to assume the appear- 

 ance of a spinous ray, as happens in the silures amongst other fishes. 

 The same thing happens likewise to one of the first rays of the dorsal 

 in the cyprins, silures, &c. ; so that these are by no means true spi- 

 nous rays, notwithstanding their appearance ; and, in point of fact, 

 these fishes, by every character which they have, belong to the 

 malacopterygians. 



The first" joints of the pectoral or ventral rays are lengthened out 

 sometimes, as in the bichir, and in such a way as to represent a 

 second row of carpal bones, and also a row of tarsal ones. 



It is un necessary for us to occupy ourselves in this part of the 

 work, with the difference in the number and proportion of these 

 rays ; they may be easily known from descriptions of the exterior 

 parts. 



We have now furnished a detail of the elements which constitute 

 the skeleton of the common or osseous fishes, and it is to be remem- 

 bered, that under this last denomination we embrace, as has already 

 been stated, a good number of the fishes to which the title of carti- 

 laginous had been given by our predecessors, in consequence of their 

 bones being less completely ossified, as the genus lophius, the 

 tetrodons, and balistes, &c. Except the vertebrae and the rays of the 

 fins, there is scarcely any difference in the number and connexions 

 of the above elements, and it is only to the differences between their 

 respective forms and proportions, that we are to assign the incal- 

 culable varieties of the general form of fishes. One set of bodies we 

 find lengthened out, other sets are either globular or prismatic, or 

 horizontally flattened, or so compressed laterally as to resemble disks 

 or edged lamina; another group of heads we find to be absolutely 

 monsters in growth, and they are angular in shape and bristled, then 

 there are others, the proportionate insignificance of which is so very 

 singular, the snouts are both short and large ; those which are pro- 

 longed into an apex or into a sword, have almost always the same 

 number of bones in their composition. 



But the chondropterygians, the only fishes which I place in a grand 

 division in relation to the combined effect of their organization, very 

 considerably differ from others in the skeleton, and we are obliged to 

 speak of them separately. What we now give is only an abridge- 

 ment, as we reserve ourselves until we come to the history of these 

 fishes, to present to the reader the details of their anatomy. 



Summary vieiti of the Skeleton of the true Cartilaginous fishes called 

 Chon dropterygians. 



The pieces of this skeleton in the selacians, that is to say in the 

 rays and sea-dogs, do not assume at all the fibrous tissue which 

 characterises the bones, the inside part remains always cartilaginous, 

 and the outer surface is indurated by very small calcareous granules, 

 which are collected on it, and which give to it the dotted appearance 

 by which they are distinguished. 



This is the reason, in all probability, why the cranium of these 

 fishes is divided by no sutures, but is composed of one continuous 



