CHIROPTERA 645 



the proximal extremity of the terminal phalanx of the fourth digit. 

 The relative development of the digits and their phalanges will be 

 noticed under each family. 



As might be expected from the small size of the posterior 

 limbs, the pelvic girdle is relatively weak. The ilia are long and 

 narrow. In the males of most species the pubic bones of opposite 

 sides are very loosely united in front, while in females they are 

 Avidely separated ; and in the family Rhinolopliidce alone do these 

 bones form a symphysis. The ileo-pectineal eminence develops a 

 long pectineal process, which in the subfamily Hipposiderince is con- 

 tinued forwards to the anterior extremity of the ilium enclosing a 

 preacetabular foramen unique among mammals. The acetabulum 

 is small and directed outwards and slightly upwards ; and with 

 this is related the peculiar position of the hind limb already noticed 

 as one of the chief characteristics of the order. The femur is 

 slender and cylindrical, with a small head and very short neck, and 

 scarcely differs in form throughout the order. The bones of the 

 leg and foot are variable ; in the subfamily Molossince alone is there 

 a well-developed fibula, while in all other species this bone is either 

 very slender, or cartilaginous and ligamentous in its upper third, or 

 reduced to a small bony process above the heel, as in Megaderma, 

 or altogether absent, as in Nycteri*. 



The foot consists of a very short tarsus, and of slender, later- 

 ally compressed toes, with much curved claws. The hallux is 

 composed of a metacarpal, a proximal and an ungual phalanx, and 

 is slightly shorter than the other four toes, each of which has an 

 additional phalanx, except in the subfamily Hipposiderince and in 

 the anomalous genera Thyroptera and Myxopoda, where all the toes 

 have the same number of phalanges as the first digit, and are equal 

 to it in length. In the genus Chiromeles the first digit is thumb- 

 like and separated from the others, and in the typical Molossince 

 the first and fifth digits are much thicker than the intermediate 

 toes. 



The most noticeable peculiarities in the myology of the order 

 consist in the separated bands or slips into which the platysma is 

 divided, and in the presence of the remarkable muscle termed 

 occipito-pollicalis, which extends from the occipital bone to the base 

 of the terminal phalanx of the pollex. 



Although, as already mentioned, the brain presents a low type 

 of organisation, yet probably no animals possess so delicate a sense of 

 touch as the Chiroptera. It is undoubtedly this perceptive power 

 which enabled the individuals deprived of sight, hearing, and smell, 

 in Spallanzani's well-known experiments, to avoid the numerous 

 threads hung across the rooms in which they were permitted to fly 

 about. In the common Bats the tactile organs evidently exist, not 

 only in the delicate vibrissae which spring from the sides of the 



