ORGAN OF HEARING. 105 



ORGAN OF HEARING IN INSECTS. 



Leaving insects for a moment out of consideration, 

 we find a mucli greater diflerence in the form and 

 structure of the ears, than of the eyes, of other ani- 

 mals. The eyes are always placed in nearly the 

 same part of the head, and consist of a transparent 

 portion more or less complicated, and a nervous 

 expansion for receiving the visual image. This uni- 

 formity, however, does not hold in the case of ears, 

 for though their situation is as constantly the same 

 as the eyes, their form is exceedingly varied. The 

 opening of the ear, for example, is admirably con- 

 trived. ' In the owl that perches on a tree,' to use 

 the words of Grew, ' and hearkens after the prey 

 beneath her, it is produced farther out above than it 

 is below, for the better reception of the least sound. 

 But in a fox, that scouteth underneath the prey 

 at roost, it is for the same reason produced farther 

 out below. In the polecat, which hearkens straight 

 forward, it is produced behind, for the taking of a 

 forward sound. Whereas in a hare, which is very 

 quick of hearing, and thinks of nothing but being 

 p-ursued, it is supplied with a bony tube, which as a 

 natural otocoustick {ear-trumpet) is so directed back- 

 ward, as to receive the smallest and most distant 

 sound that comes behind her.'* The outer ears 

 also of hounds, swine, and other animals designed 

 to hear low sounds, are either pendulous or- move- 

 able, to compensate for their difficulty of moving the 

 head ; for were their ears not so constructed, hogs 

 while eagerly digging for roots, and hounds when 

 keenly pursuing their game by the scent, might fall 

 into danger, which their hanging ears readily in- 

 timate by catching the lowest sounds that float along 

 the ground. 



* Cosmologia Sacra, i, 5, 



