304 FISHES. 



the head, and being united below constitute a bony girdle, which 

 encompasses all this part of the body. The inferior symphysis formed 

 by the union of these two series, has a ligamentous attachment to the 

 tail of the oshyoides (42), and with that bone concurs in produciug an 

 isthmus, which separates the external orifices from the branchiee of 

 each side below, as the cranium intervenes between them above. 



A small number of the osseous fishes only, such as the eels, have 

 this girdle unattached above, and diminished in the number of bones. 

 When complete it consists of three bones on each side, which 

 represent the shoulder and arm. To these are attached a group of 

 two or three other bones, which are analogous to the fore arm, and 

 have the pectoral fin as the representative of the hands. Lastly, a 

 stilet is almost always suspended from it, formed of one or two bones, 

 which appear to me to represent the coracoid bone. 



The highest of these three bones (46) is usually bifurcated, and is 

 attached by its apophyses to the two lateral crests of the cranium, 

 (the intermediate formed by the external occipital No. 9 and the 

 external formed by the mastoidean No. 12). Frequently a third 

 apophysis penetrates farther in between the two crests. This bone 

 shows itself outside, above the opening of the brachiae, like a scale 

 which is larger than the others, and some has its margin with inden- 

 tations ; it is deficient in some genera, as in the eels, and in lophius ; 

 it is united to the cranium by a fixed suture, as in the flying fishes 

 and some species of silures. 



The second of these bones (No. 47) is part of the margin ; but it is 

 wanting in the silures, in which species 'we find it soldered into a 

 single piece, with the first bone. The third (No. 48) which is always 

 very much the largest, completes the girdle as it proceeds, as we have 

 already mentioned, to unite with its fellow from the other side 

 beneath the throat. It frequently gives out above the base of the 

 pectoral fin, a spine or indented angle, and generally is composed of 

 two laminae; between these laminae, one of which is external, and the 

 other internal, is a furrow in which the inferior fasiculus of the great 

 lateral muscle of the body terminates, and which is moreover occu- 

 pied by the muscles of the pectoral fin. 



In the eels, this third bone takes the form of a simple cylinder com- 

 pressed and arched. It remains still in some fishes that do not possess 

 the pectorals, as for example, the Symbranchise, in which it is even 

 very strong, and in which also we cannot find a trace of the second 

 bone. But in the murena (murceni helena), this third bone is no 

 more than a long cartilaginous filament, which is only found in the 

 flesh after a great deal of labour. 



Almost always its union with that of the other side, takes place by 

 cartilages or ligaments ; but sometimes also as in the silures, and the 

 genus platycephalus, the junction by a large indented suture. 



on the osteology of this class. He has produced the greatest part of it in his 

 Philosophie Anatomique, vol. i. p. 407, and the following pages. 



We have figured the bones of the shoulder in their connexion with the cranium, 

 by their external surface, pi. iii. fig. 1 . ; also detached from the cranium, hvit the 

 union still remaining, the inside surface being presented fig. ih., and fig. ii. these 

 bones completely separate it. 



