INTKODTJCTION. xix 



nene ; for, as the latter organ collects the waves of sound, so the 

 former receives impressions arising from vibrations communicated 

 to the air by approaching objects. 



But although the sense of touch in the leaf-nosed Bats must evi- 

 dently be immensely increased by these nasal appendages, it should 

 not be lost sight of that this sense is extremely acute also in species 

 not provided with such special organs. In Spallanzani's well-known 

 experiments, the Bats which succeeded in avoiding numerous threads 

 hung across the rooms in which, when deprived of sight, hearing, 

 and smell, they were permitted to fly about were not leaf-nosed 

 species ; and the i;nerring flight of the simple-nosed Bats of this 

 country, even in the darkest places, has been observed by almost 

 every one. We must therefore seek for other sensory organs which 

 supplement the sense of vision. These undoubtedly exist in the 

 great extent and highly sensitive condition of the integument enter- 

 ing into the formation of the wing-membrane and ear-conch*. In 

 many of the species of Vesjpertilionidce also the concave surface of 

 the large and delicately formed ear is dotted over by numerous 

 minute glandular elevations, from which smaU straight hairs, evi- 

 dently analogous to the vibrissse on the sides of the muzzle, arise 

 (see Plate XVII. fig. 7). 



In no order of Mammals is the ear-conch so greatly developed or 

 so variable in form. In some of the species of the group Plecoti 

 the length of the ear nearly equals that of the head and body, 

 while in by far the greater number of the species of Microchiro- 

 ptera the ears are as long or nearly as long as the head, and in many 

 species they are united across the forehead. The form of the conch 

 is very characteristic in each of the families. In Nycteridce, Ves- 

 pertilionidce, Emballonuridce, and PTiyUostomidce the tragus is 

 greatly, developed, forming in some species a long projection ex- 

 tending nearly to the outer margin of the conch, and its shape is 

 generally characteristic in each species. Its office appears to be to 

 cause undulations in the waves of sound, and so intensify and pro- 

 long them. It is worthy of notice that in the truly insectivorous 

 JRMnolopliidce, where the tragus is not developed, the auditory bullce 

 ossece reach their greatest size and the highly sensitive nasal ap- 

 pendages their highest development; also in the group Molossi the 



* See an excellent paper on the minute anatomy of the wing-membrane in 

 Ohiroptera, by J. Schobl, in Schultze's 'Archiv,' vii. (1871) pp. 1-31, in which 

 the layers of integument, the hairs and their glands, the mode of termination 

 of the nerves, &c. are carefully described. 



