August, 1S99.] 



169 



THE NATURAL HISTORY OF IRISH BATS. 



BY N. H. ALCOCK, M.D. 



The Hairy-Armed Bat. 

 Vcspaugo (Pipistrellui) Lculcri, Kuhl. 

 [Plates 7 and S\ 

 This handsome species is one of the most easily recognised 

 and studied of our Irish Bats, and as it occurs very abundantly 

 near Dublin it has been possible to ascertain some interesting 

 details of its life-history with more precision than was 

 practicable in other districts, where this bat is merely an 

 uncommon visitor. 



Three principal characteristics serve to distinguish this 

 species from those with which it might be confounded. 



1. The size. 



2. The fur. 



3. The teeth. 



The measurements given by Dobson (iv., p. 216), are : — 



Many individuals are slightly larger than this, the length 

 being sometimes as much as 2-6", forearm 1 • 68", 3rd finger 

 3-0", 5th finger 1-97". 



The fur is of a fine chestnut colour above, the terminal one- 

 fourth of the hairs being bright yellowish, the basal three- 

 fourths dark brown ; below, the terminal one-fourth is light 

 brown, the basal part dark brown. The fur is said to be 

 darker in young individuals than in old. In several specimens 

 I examined, the males were darker than the females, in others 

 not ; this may possibly be an example of age difference, but 

 further investigation is necessary to decide the question. 



The incisor teeth furnish another distinguishing charac- 

 teristic. The outer upper incisor is equal to the incisor in 

 cross section at the base, while the lower incisors are said to 

 stand in the direction of the jaws, and not to be " crowded." 



a 



