84 BRITISH MAMMALS 



the whole of the tail, practically, is contained within the flying 



membrane. The index finger in each hand has two phalanges, 



or joints. These bats, in common with most of 



the Microcheiroptera, have developed a bony spur 



(calcaneum), which grows almost at right angles 



from the ankle (inwards towards the tail), and 



serves to support the interfemoral membrane. This 



membrane is also supported by what appears to be 



another spur of bone, but which is really the stumpy 



fibula.^ The apertures of the nostrils, though 



Bones of a Bat's sometimes hidden in deep grooves, are without 

 Leg and Foot. , ^ ,, 



any excrescence or " nose leaf, except in two 



non-British genera in which a rudimentary excrescence or nose 



leaf occurs above the nostrils. 



Genus: VESPERTILW^ 

 In this genus of bats, and in the two succeeding genera, 

 Pterygistes and Pipistrellus^ the ears are comparatively small, and 

 situated rather wide apart. The outer margin of the ear is 

 extended to and ends at the angle of the mouth, where it 

 thickens into a rounded lobe. The inner margin of the ear curls 

 round somewhat sharply at its base into another lobe, situated 

 quite close to the small eye. The tragus, or flap covering the 

 entrance to the ear, is short and thick, and curves towards the 

 inner margin of the ear. The muzzle is short, broad, and blunt, 

 rather like that of a frog, and there are prominent swellings 



^ The smaller and second bone of the leg. 



2 In the classification of British bats the author follows — not altogether 

 confidently — the authorities at the British Museum (Natural History) in their 

 most recent nomenclature, and departs somewhat widely from that great 

 authority on bats, the late Dr. G. E. Dobson. The new classification of 

 British bats is due to the researches of an American zoologist, Mr. G. S. 

 Miller, and of Mr. Oldfield Thomas. In this arrangement the old generic 

 term Vesperugo is abolished (according to the law of priority) in favour of 

 Vesperlilio, and is further divided into Pterygistes and Pipistrellus. The 

 Vespertilio of Dobson and others becomes Myotis. Vesperugo discolor becomes 

 Vespertilio murinus, while the totally distinct Vespertilio murinus of Dobson 

 {Myotis myotis) is not always recognised as a British species. 



