266 THE BIOLOGY OF INSECTS 



countries it is known to abound, and naturalists collecting 

 insects in the far north find it common on the coasts of 

 Spitsbergen, in Novaya Zemlya and in Greenland. Probably 

 it inhabits all the continents of the globe, as it has been 

 recorded from Tierra del Fuego, from New Zealand, and 

 from small, sub-antarctic islands to the southward. Many 

 other species of Achorutes have a known range nearly as 

 wide as this, while a closely allied genus (Gomphiocephalus) 

 and an obscure Isotomine springtail are the only non- 

 parasitic insects as yet discovered by explorers of the great 

 Antarctic Continent. G. Taylor has described (1914) how 

 at Granite Harbour in South Victoria Land Gomphio- 

 cephalus swarmed on the surface of a small pool or clustered 

 in a film of ice : " as one turned a pebble to the sun they 

 would thaw out and crawl around for exercise." Delicate 

 white and blind springtails (Onychiurus) are among the 

 commonest members of our " soil fauna," often congregating 

 in hundreds on soft plant tissues and decaying vegetable 

 matter. One of this group — Onychiurus armatus — has nearly 

 as wide a range as the Achorutes just mentioned, and is 

 among those insects recorded by E. Handschin (1924) as 

 present in the Swiss Alps to a height approaching 10,000 feet. 

 Several species of springtail have long been known to 

 disport themselves on the surface of the high Alpine snow- 

 fields where masses of darker coloured Achorutes may appear 

 as blackish patches conspicuous on the pure white back- 

 ground. And while such members of the order live far 

 up the mountain heights, a considerable number of the 

 springtails form a relatively large section of the fauna of 

 deep caves. Among the white species mentioned above as 

 living in the soil, is Onychiurus hiermis ; this insect is found 

 commonly in the deep galleries of caves excavated in the 

 Carboniferous Limestone districts of Great Britain and 

 Ireland. All the species of Onychiurus are eyeless, and 

 most of the springtails inhabiting caves are white and blind, 

 even if they belong to groups whose members are normally 

 provided with eyes. While some of the British and 

 European cave springtails — such as Heteromurus margari- 



