310 



THE SENSORIAL FUNCTIONS. 



mentioned by Camper, of enclosing a marble in a bladder 

 full of water, and held in the hand; when the slightest shaking 

 of the bladder will be found instantly to communicate mo- 

 tion to tiie marble, the reaction of which on the bladder gives 

 an unexpected concussion to the hand. 



The ear of Fishes contains, in addition to the vestibule, 

 the three semicircular canals, which arc, in general, greatly 

 developed.* An enlarged view of the membranous laby- 

 rinth of the Lophiiis piscatoruis is given in Fig. 403, show- 

 ing the form and com})lication of its parts, which are repre- 

 sented of twice the natural size, x, y, z, are tlie semicircular 

 canals, with their respective ampullae (a, a, a.) m is the 

 Sinus rtiedianus^ or principal vestibular sac, with its ante- 

 rior expansion, termed the Utricle (u.) The Saccidus (s) 

 has, in like manner, a posterior appendage (c) termed the 

 Cysticule. The hard calcareous bodies (o, o, o) are three 

 in number; and tlie branches of nerves (i, i, i) by which 

 they are suspended in the fluid contained in the membranes, 

 are seen passing into them; while the ampullae are supplied 

 by other branches (n, n, n.) In all the osseous fishes, the 



labyrinth is not enclosed in the bmies of the cranium, but 

 projects into its cavity; but in the larger cartilaginous fishes, 



♦ In the lamprey, these canals exist only in a rudimental state, appearing" 

 as folds of tlie membrane of the vestibule; and there are also no cretaceous 

 bodies in the vestibular sac. 



