92 ZOOLOGY 



The principal large cave animals are various bats, which are 

 found clinging to the walls ; a few salamanders, allied to our 

 Uttle red salamander of the woods (Fig. 95) ; and certain fishes, 

 many of which are blind. A number of insects live in caves. 

 The commonest are two or three kinds of 

 small beetles that live under stones and a 

 few flies that hve in decaying matter; a 

 cricket-grasshopper, already referred to on 

 page 20; a little "spring-tail," the minute 

 insect which swarms on the damp rocks. 

 There are also a few myriapods, which we 

 shall studj' further in this chapter; some 

 spiders ; a blind cray fish, which lives in the 

 streams that usuallj' fiow through caves ; 

 and a few smaller crustaceous animals. 

 Each of these groups is more fully con- 

 sidered in the folio-wing paragraphs. 



The bats, of which about 500 species from 

 all parts of the globe are known, constitute 

 "•'„ one of the most specialized groups of Mam- 



^v mals. They are able to 



"~^1.:^ .-;-__. _ fl}^ owing to the great 



"""--v..^^^^ elongation of their fin- 

 FiG. 95. — Adult of Six'lerpos mar-uiicaudus, gers and to a delicate 

 the cave .saiamaiids-r. membrane stretched be- 



tween them. They fly almost exclusively at night or toward 

 dusk ; and they seem to be guided less by tlieir eyes than by 

 the vast number of delicate organs of touch that are scattered 

 over the wing membrane. Also the tip of the nose is crowded 

 ■with touch organs, which are often borne on a fantastically 

 folded membrane. The outer ears are usually very large, 



