64 



been recorded from Argentina, Sumatra, tlie Sandwioli 

 Isles, and the Bismarck Archipelago, and also from the 

 Azores. Among species, Aehorutes armahis is found 

 throughout the greater part of the Holarctic region, as 

 well as in South America, New Zealand and Sumatra ; 

 and Sminfhunis hortensis has a wide distribution in 

 northern and central Europe, and is also known from 

 North America, Tierra del Fuego, and Japan. 



In colouration a wide range is exhibited among the 

 various species. Many forms are of a uniform dull blue- 

 black, as in Anurida; others are green or yellowish, with 

 irregular patches of a darker colouring ; a few species are 

 banded or ringed ; some are all white ; and metallic forms 

 are not infrequent. 



In the greater number of Collembola the body is 

 clothed with hairs, but in some genera, such as Tomncerux 

 and Lepidocijrt\is, it is scaled, although hairs are not 

 altogether wanting. The hairs (text-fig. 4) may be simple 

 and tapering, clavate, or flattened and partially resemb- 

 ling scales, OT compound as in the Entomobryidse. The 

 scales bear a close resemblance to those of the Lepidoptera 

 but, acording to Sommer (23), they differ from them in 

 that they have no connection with the underlying 

 hypodermis. They are familiar to microscopists on 

 account of their being favourable test objects for the 

 capabilities of high power objectives. 



The head varies considerably in the three families. 

 In the Smintliurid?e it looks almost vertically downwards, 

 among the Entomobryidae it is also pointed downwards, 

 but in rather an oblique direction, while in the 

 Achorutidse it is directed straight forwards in a line with 

 the rest of the body. The antennae have from four to six 

 joints ; they may be short and stout, as in the 

 Achorutidtc, or long and slender, as in OrrJiese/Ia and 



