270 PROCEEDINGS OF SECTION D. 



The order is divided into two sub-orders, Arthropleona and 

 Symphypleoiui. The former have an elongated and sub-cylindrical 

 body, whilst the latter are sub-globular, the segments of the abdomen 

 almost fused together. 



The sub-order Arthropleona contains two families. Of these the 

 Entomobryidae contains the largest members of the order, though 

 many of the species are minute. The family is divided into three sub- 

 families, of Avhich the Isotominae are represented in Western Australia 

 by a large black and yellow species found under logs in damp situations. 

 Superficially it much resembles Isotoma aquatilis, a common British 

 species, but differs in certain structural details, which will probably 

 require for it the creation of a new genus. Isotoma troglodytica, 

 Eainbow, presumably belongs here. Of the second sub-family Tomo- 

 cerinae, which are so common in England, I have found no represen- 

 tatives, but of the third sub-family Entomobryinae, I have obtained a 

 number of forms. This sub-family is again divided into four tribes, 

 of which the Entomobryini are represented in my collection by species 

 of Entomobrya, Sinella, and Lepidocyrtus, as well as by a species 

 which seems to belong to a new genus. The Orchesellini are repre- 

 sented by a species of Heteromurus, black with white bars on the 

 abdomen, common under bark, and what is apparently another species 

 of the same genus of a chestnut colour. The tribe Cyphoderini com- 

 prises a single genus, whose species are all found in ants' nests. They 

 are blind, white, and scaleless. I have found a species in Western 

 Australia in the nests of several species of ants. 



The family Poduridae consists of 'Collembola without a spring 

 or with the spring much reduced. The species generally occur in great 

 numbers when they are present. 



One group of genera are quite white and blind, and live in decaying 

 vegetable matter underground. I have found a species of this type 

 feeding in rotten potato-tubers near Perth. 



A second group of forms are brown or purple in colour and possess 

 a pair of curved hooks on the last segment of the abdomen. The genera 

 Anoura, of which Lubbock has described three species from under logs 

 in Tasmania, and Achorutes, of which Rainbow describes a species 

 from the surface of a pond at Bathurst, belong here. !l found a species 

 in considerable numbers on the water which stands in the hollows 

 from which guano has been dug on the Abrolhos Islands. I have also 

 found a species of this group feeding on fungi in Western Australia. 



The genus Anurida, which also belongs to this family, is of special 

 interest, because some of its species live in the sea, Anurida maritima, 

 which is found in Europe and North America, is common on the English 

 coasts, occurring on rocks, shingle, or mud-flats. At low tide the little 

 insects crawl about and eat any small plankton forms which may have 

 been stranded. At high tide they creep into crevices in the rocks 



