184 ORDER CHEIROPTERA ; GENERAL CHARACTERS. 



the wing, whilst it is small or entirely wanting in those which 

 live on fruits. In their mode of flight, Bats bear a very strong 

 resemblance to Swallows, which like them pursue insects on the 

 wing ; but whilst the latter seek their food during the day, the 

 former come forth only at twilight ; and thus the Bats exercise the 

 same purpose in the economy of Nature, in restraining the multipli- 

 cation of the crepuscular (twilight-flying) and nocturnal insects, 

 as the Swallows do in regard to the diurnal. During the day, the 

 Bats sleep in their recesses, suspended by their hind-feet, their 

 heads consequently hanging downwards (Fig. 92) ; and they 

 assume the same position during the whole winter, which is 

 passed by them (in our climate at least) in a state of torpidity. 



167. The senses of hearing and smell are developed in Bats 

 to an extraordinary degree ; as we might judge by the size of 

 the organs, especially in the insectivorous species. In the long- 

 eared Bat of this country (Fig. 91), the external ear is nearly as 

 long as the body ; and there is frequently an inner fold, which 

 seems like a smaller ear within the principal one. The nose, 

 again, frequently presents an extraordinary development, being 

 furnished with curious leaf-like appendages, formed by a prolon- 

 gation of the skin, which is folded and doubled in various direc- 

 tions, so as frequently to present a most grotesque appearance. 

 The membrane of the wing, too, is endowed with a very high 

 degree of sensibility, so as to receive impressions from the resist- 

 ance of the air, which guide the animal in its flight through the 

 darkest recesses, preventing it from striking against obstacles, 

 even in a complete labyrinth (ANIM. PHYSIOL. 495). The 

 eyes are usually small, and can be of little use to those which 

 pass nearly their whole time in obscure caverns, or in the dark 

 chambers of old buildings. On the other hand, the frugivorous 

 species, which sail over gardens, plantations, or forests, in search 

 of their food, are guided chiefly by their sight ; their eyes are 

 accordingly rather large than otherwise, whilst the ears and nose 

 have no extraordinary development. 



1 68. The insectivorous, or insect-eating, Bats constitute by 

 far the largest division of the Order ; they are recognised, not 

 only by the characters already noticed, but by the conformation 



