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internal ear: that in those forms in which it has an auditory 
function, we perceive two very distinct modifications, in marine 
Physoclisti a prolongation of the air-bladder itself passes 
forwards to the interior of the skull, while in fresh-water 
Physostomi the connection is by means of a string of auditory 
ossicles; that in such fishes as live the life of ground feeders a 
still further modification may take place, in the air-bladder 
itself being more or less completely surrounded by osseous 
walls, formed by the growth of the parapophyses of some of 
the anterior vetebrz, 
