INTRODUCTION. 75 



circular canals are often largely developed. In the 

 osseous fishes, to a part of which this volume is 

 more particularly devoted, the whole of the 

 labyrinth of the ear projects into the cavity of the 

 cranium. The labyrinth is filled with a trans- 

 parent liquid, distending the vestibule and sack, 

 which contain small and peculiar bony substances, 

 two or three in number, which float in the liquid, 

 and would apparently convey the sense of any 

 concussion to the nervous linings of the edges, 

 and upon the principal plexus of the auditory 

 nerve, which is ramified in the greatest proportion 

 on the walls of the sack, which generally contains 

 the largest of these hard osseous bodies. The 

 structure of the ears in fishes is certainly less per- 

 fect and less complicated than in the higher 

 mammalia and birds ; and Cuvier is of opinion, 

 that though they hear sounds distinctly, or as 

 concussions, yet they are unable to distinguish 

 any of the finer tones or variations. That they 

 are sensible of the impulses of sound has often 

 been proved, and fish are known to approach for 

 food at the whistle of their keeper.* 



Smelling, again, appears to be even farther 

 developed than what is generally supposed. The 



* The Romans were even said to have taught each 

 to approach upon calling by a particular name. Fre- 

 cynet, speaking of the Squahis melanopterus which the 

 expedition met with at the Waigow Islands, says they 



