STRUCTURE OF FISHES. 421 



there are no ribs. Where these bones exist, 

 they are articulated with the extremities of the 

 transverse processes of the vertebra, of which 

 they appear to be merely continuations, or ap- 

 pendices. There is generally no sternum to 

 which they can be attached below : in a few 

 fishes only, such as the herring and the dory, we 

 find rudiments of this bone, consisting of a few 

 pieces placed in a line on the lower part of the 

 trunk.* 



The parts of the skeleton of fishes, which cor- 

 respond to the arms and legs of quadrupeds, are 

 the pectoral and ventral fins (marked respectively 

 by the letters p and v in Fig. 184). The former 

 are met with, with but few exceptions, in all 

 fishes ; and they consist of a series of osseous 

 pieces, in which we may often recognise with tole- 

 rable precision the analogous bones composing 

 the anterior extremities of a quadruped ; such as 

 the scapula, clavicle, humerus, ulna, and radius. t 

 These two latter bones are very distinctly marked 



* The bony arches arising from the skull, which support the 

 branchiae, or gills, have been considered as the bones correspond- 

 ing to the ribs of terrestrial quadrupeds ; and if this view were 

 taken of them, it would tend to confirm the analogy of the cra- 

 nial bones to the spinal vertebrae. 



f Those anatomists who are fond of pursuing the theory of 

 analogies, maintain that all these bones are merely developements 

 of certain ribs, proceeding from the spine in its anterior parts. 

 A similar origin has been assigned to the pieces of bone to which 

 the ventral fins are attached : but it is difficult to reconcile this 



