MILLIPEDES 33 



be correlated with the fact that egg-laying is an interrupted process 

 and the female lays her eggs in small groups in several places, 

 usually buried in loose soil and always under cover of moss or 

 dead leaves. The British Opisthospermophora begin their breed- 

 ing rather later in the year than do the Polydesmids. 



In some species of millipedes the eggs are coated with earth and 

 excrement and then left in crevices in the soil; in others a nest is 

 constructed of soil particles that have been moistened with saliva. 

 When completed, the nest has the shape of a hollow sphere. The 

 inside is lined with dried excrement and is smooth and even, 

 whereas the outside is rough and irregular. Sometimes the female 

 does not leave the nest immediately, but remains for several days 

 curled round it so tightly that she is difficult to remove. 



When the female Glomeris marginata is about to lay she rolls 

 over on her back and the little egg is passed backwards from seg- 

 ment to segment until it arrives at the end of the body. There it is 

 held immediately over the anal region and the rectum is everted to 

 a considerable extent so as to form a mobile pad holding a small 

 quantity of very fluid excrement which is carefully plastered over 

 the egg. When dry this forms a spherical chamber in which the 

 Qgg lies freely. Occasionally two or three eggs are enclosed in one 

 mass, but always in separate compartments. InPolydesmus angustus 

 and other Proterospermophora and Colobognatha, all the eggs are 

 enclosed in a common covering. The nest is like a thin-walled, 

 dome-shaped tent surmounted by a narrow tubular chimney. It is 

 built on some firm substratum — a stone, a leaf, the inside of an 

 acorn cup, or the inner surface of a piece of bark — and is con- 

 structed with the mobile surface of the extroverted rectum. The 

 female first gnaws a small cavity on the surface on which she in- 

 tends to lay. Then she bends herself into a circle and walks round 

 and round, leaving a rapidly drying blob of excrement as she goes, 

 until the concave spot is surrounded by a rampart, the circum- 

 ference of which is slightly greater than the length of her body. 

 When the nest has reached about two-thirds its full height the 

 eggs are laid. The female lies across her nest and the eggs drop in 

 one after the other, sticking together as they fall. The nest is then 

 roofed over and the chimney completed with the aid of the everted 

 rectum and the supra-anal process which possesses six tactile 



C S.S.C.M. 



