THE BATS 91 



the German Fledermaus. " Bat " is a word of Scandinavian origin, 

 and is a corruption of bakke, which again is an abbreviation of 

 blakke, a word which meant " to flap." This term " bat " came 

 into use in English after the Norman Conquest, and gradually- 

 spread from the east of England into the literary language, 

 "flittermouse " only surviving in country speech. 



The Pipistrelle is the smallest of the English bats, and 

 measures at most i|- in. from the tip of the nose to the base of 

 the tail, while the tail is scarcely i J in. in length. Its head is 

 more rounded than that of the hairy-armed bat, but the nose and 

 muzzle are less blunt than those of the noctule. The ears are 

 fairly large, and are nearly triangular in shape, resembling in 

 outline very much the 

 wings of a butterfly. 

 There are well-developed 

 glandular swellings on 

 the muzzle, and the face, 

 including the region of 

 the eyes, is nearly devoid 

 of hair in full-grown 

 specimens. The thumb head of pipistrelle or common bat 



,1 1 1,1 (Pipistrellus pipistrellus). 



is rather weak and the 



feet are small, with very fine claws. The innermost pair of the' 

 upper incisor teeth have bifid crowns — that is to say, they seem 

 almost as though they were divided into two teeth in the middle ; 

 nor are they set quite straight in the jaw, for the innermost 

 divisions of these teeth project forward more than the outer 

 section. There are four incisors in the upper jaw and six in the 

 lower. Those in the lower jaw are divided into three lobes, in 

 contrast to the upper incisors, which, as already mentioned, 

 have each of them two divisions. There are two pairs of pre- 

 molars and three pairs of molars in each jaw. On each side of 

 the nose above the upper lip is a protuberance covering the 

 sebaceous glands, which add to the swelling of the muzzle. The 

 eyes are very small and deeply sunk. Over each eyebrow is a 

 small wart, from which spring a few black hairs. On the top of 



