BRITISH BATS. 35 



thumb, the bat can climb with great ease up the 

 rugged surfaces of walls and the bark of trees ; but 

 on level ground its progression is extremely awkward. 

 It first moves forward the hook on the wing so as 

 to take hold of any slight projection, and then 

 advances the hind foot on the same side, thus 

 tumbling forward in a succession of clumsy jerks. 

 In climbing up walls they crawl backwards, raising 

 themselves against the object they desire to scale, 

 and moving up by the alternate use of their hinder 

 feet. 



When resting they suspend themselves head 

 downwards, so as to enable them, if desirous of 

 taking flight, to do so by merely expanding their 

 wings, and releasing their foot-hold. In this 

 singular position they hibernate during the winter 

 in a state of lethargy. Church steeples, hollow 

 trees, old barns, caverns, and similar situations 

 form their favourite retreats, and vast numbers are 

 often found crowded together and forming a com- 

 pact mass. One hundred and eighty-five were on 

 one occasion taken beneath the eaves of Queen's 

 College, Cambridge ; they were all of the same 

 species, the noctule (Noctulinia altivolans), almost 

 the largest species found in England, commonly 

 measuring from fourteen to sixteen inches in ex- 

 panse of wing. The pipistrelle, our most common 

 species, and the long-eared bat (Plecotus auritus) 



D 2 



