34 MILLIPEDES 



hairs. When the nest is finished the female does not leave it im- 

 mediately but remains coiled around it for about a week. She 

 covers it with bits of leaves and wisps of grass and will replace 

 them over and over again if they are removed (Evans, 1910). 

 Oxidus gracilis females, however, deposit their eggs in small rough 

 cavities from 3 to 15 mm below the surface of the soil, but do not 

 construct brooding chambers nor remain with them during the in- 

 cubation period. 



In contrast, most of the Opisthospermophora construct a very 

 crude nest which is mainly built from the inside, only the top being 

 laid on from the outside. The female burrows into loose soil until 

 she comes to a firm foundation, usually a stone, where she pro- 

 ceeds to make a dome-shaped clearing, the shaping being done by 

 her jaws. This space is then plastered from the inside with liquid 

 excrement by means of the everted rectum, the animal meanwhile 

 having to assume some very awkward positions during the process. 

 On emerging from the recess she pushes her way into a position 

 astride the open top and lays her eggs. After closing the hole she 

 pays no further attention to her nest (Evans, 1910). 



The function of the nest building described above is to protect 

 the eggs and young from attack by fungi which are an ever present 

 menace, as they are to the young stages of woodlice, and also from 

 the cannibalistic proclivities of the males of the species. In a simi- 

 lar way Polymicrodon polydesmoides spins a silk tent for the purpose 

 of moulting and also to cover its cluster of eggs. After a moult it 

 eats the silk. 



The Blaniulidae lay their large, elongated eggs singly, however. 

 The Spirobolid millipede Arctoholus marginatus of North America 

 manufactures the cases in which her eggs are individually en- 

 closed with material regurgitated from her mouth. The moist 

 lump is held by the legs of the eighth to eleventh pairs and shaped 

 with the convex front of the head. A shallow bowl is made into 

 which an egg is laid. The sides of the bowl are then drawn up 

 over the egg and kneaded together until a perfect sphere is pro- 

 duced. The completed pellet is dropped by the mother who then 

 starts the next (Loomis, 1933). In many species, on the other hand, 

 the eggs are never covered. 



The number of eggs laid by millipedes varies considerably 



