THE VERTEBRAL COLUMN OF FISHES. 175 



shark is composed of upwards of two hun- 

 dred. 



When we speak of the ribs of fishes, it must 

 not be supposed that they subserve the same 

 purpose as the ribs in quadrupeds or birds ; 

 they are imbedded in the muscles of the sides, 

 to which they give attachigent, and, in many 

 fishes, are furnished with numerous slender 

 appendages, buried also among the muscular 

 fibres. In the herring, these are very abundant. 

 We shall not here notice the interspinous bones 

 running down the ridge of the back, nor those 

 forming the fin-rays, which are either hard and 

 spinous, as in the perch, or soft and cartilagin- 

 ous, (with the exception, sometimes, of the 

 first dorsal and pectoral rays,) as in the salmon, 

 trout, cai'p, etc. These bones must be regarded 

 as appendages, which are infinitely varied, and 

 which do not necessarily enter into the com- 

 position of the spinal column even as adjimcts. 



We have described the structure of the ver- 

 tebral column as we find it in the osseous 

 fishes — fishes in which the skeleton is the most 

 completely ossified — and altogether the most 

 elaborate. There is, however, an extensive 

 group of fishes in which the skeleton is never 

 ossified, but remains permanently in a state of 



