i899-] Ai,cock. — The Natural History of Irish Bats. 31 



forming the fingers are enormously lengthened. The whole 

 arm thus forms a light and strong frame- work over which the 

 skin of the body is prolonged to form the wing-membrane. 



On the trunk are found powerful muscles to work the wings, 

 and within are the large lungs and heart, to furnish a 

 sufficient supply of pure blood over this large area. 



The hind limbs are comparatively small and weak, and the 

 knee is directed backwards, the only instance of this position 

 in the Mammalia. The tail is of considerable length, and 

 included in the well-developed interfemoral membrane ; the 

 tip is often free, and used in climbing. 



The digestive system follows the usual mammalian type, and 

 the points to be here noted are few. The intestinal canal is 

 short, as a rule, and the stomach capacious. There are well- 

 marked intestinal villi. The liver is much divided into lobes ; 

 the microscopic structure of both it and the spleen presents 

 nothing unusual. 



The nervous system and the organs of special sense will be 

 considered later, along with some interesting questions 

 connected with them. 



The habits of these seven species are not known with 

 accuracy in all cases. 



All, as a rule, sleep during the day and come out in the 

 evening, the. time of flight varying with the species and the 

 time of sunset, possibly also with the weather and the place. 

 Accurate figures have usually not been given ; as a mean of a 

 few observations made in September, 1898, at Bray, Co. 

 Wicklow, it would seem that the Hairy- armed Bat appears 

 about 26 minutes after sunset, 1 the Pipistrelle 33 minutes, 

 and Daubenton's Bat 54 minutes, the time being that at 

 which the first bat was seen in the open. T. A. Coward (iii.) 

 gives 70 minutes after sunset for DaUbenton's Bat in Cheshire, 

 this being the time when the first bat flew along the water- 

 not necessarily the time of flight, as he remarks. Borrer (ii.) 

 states that at Ulleswater and Grasmere this species flies by 

 night over the lakes, and by day in the boat-houses, so 

 burning the caudle at both ends ! 



1 The local time of sunset must be taken in each case. See C.V. 



Boys C.T.C. Gazette, November, 1898, or Whitaker's Almanac, for the 



necessary calculations. 



A 2 



