158 ME. E. T. niGGINS ON THE OTOLITES OE EISH. 



various modifications of tlie auditory apparatus of other members 

 of tlie animal kingdom for comparison. The auditory organs con- 

 sist of a contained fluid and of a solid body or bodies, with which 

 the fibrillas of the acoustic nerve are in close communication ; but 

 in order to render this simple form available for the recognition 

 of delicate modulations, and give judgment of the distance and 

 position of the vibration, a more complicated apparatus is given 

 to the higher orders of the Yertebrata. "We find in the Eeptilia 

 a drum or tympanum to receive the vibrations and transmit them, 

 by means of an ossicle called the columnella, to the internal ear ; 

 a canal bent upon itself also makes its appearance, which may be 

 looked upon as a rudimentary cochlea. A similar, though slightly 

 modified, arrangement exists in birds. In Mammalia, in whom 

 the powers of hearing are more acute, and whose power of appre- 

 ciating modulations is more sensitive, we have an acoustic instru- 

 ment of the most perfect description, consisting of a chain of four 

 ossicles, a well-developed cochlea, tympanum, and external ear. 

 By many naturalists the circular arrangement of feathers sur- 

 rounding the external opening of the ear in some birds has been 

 looked on as the equivalent of the external ear in Mammalia ; it 

 must, however, be but an imperfect representative. 



As, however, sonorous vibrations communicated to water pass 

 through it with great intensity, it is absolutely necessary that a 

 considerable modification of the auditory organs of its inhabitants 

 should exist, or they would be perpetually liable to injury, or even, 

 death, from the violence of vibratory shock ; we therefore find, 

 as might be anticipated, a much simpler form of auditory appa- 

 ratus in fish, deprived of external ear, tympanum, and cochlea, 

 though it has been stated that a rudimentary cochlea does exist 

 in some fish. This rudimentary form will at once suggest that 

 fish derive their sense of hearing from other sensations than such 

 as we term sound, and receive over the whole surface of the body 

 vibrations which are conveyed to the internal ear. That a fish 

 does not possess hearing in any other than a very simple degree 

 is capable of proof ; and we have frequent and direct evidence that 

 they have no sense of either the direction or the immediate vici- 

 nity or distance of the source of the vibrations which disturb them. 

 The experience of fishermen confirms this. A shoal of fish taking 

 the bait freely will be disturbed, and sink at once to the bottom 

 of the water, on the rounding of a point by a steamer, though 

 at an immense distance, with as much alarm as if the danger 

 threatening them were in the immediate neighbourhood. With- 



