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ABSTRACT OF A PAPER ON BATS. 



Bt JAMES RANKIN, Esq., M.A., President. 



I. The Order of Bats, on account of their nocturnal habits and peculiar 

 aerial mode of progression, is perhaps less known than many orders which are in 

 reality less common. I therefore propose to make a few brief remarks upon 

 these very interesting animals. ' 



On looking at any Bat, the first thing which strikes one is the curiously- 

 extended arm and fingers and the membrane supported by them, forming what 

 is called the wing. On examining this structure closely, we find that this 

 membrane is double, being in fact an extension of the cuticle of the upper and 

 under sides of the body. 



The fore-arm is much lengthened, and the radius does not rotate upon 

 the xdna, thereby gaining strength for the stroke of the wing. The thumb or 

 pollex is always short and clawed, the four fingers immensely elongated. 



The hind limbs are of proportionate length to the size of the body, and 

 the toes are always free from the membrane and clawed ; the membrane extends 

 between the hind legs, and in those species which have a tail the membrane 

 usually extends as far as the end of that member. 



The hind limbs of Bats perform the functions of the fore limbs of most 

 other animals which use their hands or paws for grasping, and in relation to 

 this change of functions we find in Bats a very curious change in the plan of 

 rotation of the hind limbs ; these members are in fact turned round so far as to 

 appear to be set on the body backwards, that is to say the knee joint acts back- 

 wards like the elbow, and the feet are turned with the soles upwards and the 

 big toe outside, which arrangements are the reverse of what is found in other 

 animals. 



It should be noticed, however, that the muscles, bones, &c., are those of 

 the hind limbs, and not those of the fore limbs, showing that although their 

 functions are altered, yet their homological relations are preserved. 



Looking now at the body of a Bat, we find it more like a mouse or shrew 

 than any other animaL Bats vary considerably in size, but the common English 

 Bat is about 2j inches long. The head is long and the ears are large, and in one 

 kind of Bat (the long-eared Vespertilio Aurilus) the ears are half as long as 

 the body. 



The brain is smooth, and the cerebral lobes do not cover the cerebellum. 

 In this respect Bats agree with the Insectivora and Rodentia. 



