286 Mr. T. J. Evans — Bionomical Observations 



the female rolls over on her back, and the little egg is passed 

 backwards from segment to segment by the feet 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. This is carefully plastered on to 

 the under surface of the egg and held there until the fluid 

 gradually filters back into the intestine. As soon as the thin 

 layer of excrement is sufficiently firm, the egg is turned round 

 through a small angle and the process repeated until the 

 whole egg is plastered over at least twice. In this way the 

 egg is enclosed in a shell about \ mm. in thickness and 

 2 mm. in total diameter. When the ca3e is complete, the 

 female tilts it over to the ground, and may right herself or 

 proceed to lay and enclose another. 



When the case is firm and dry the egg lies freely in a 

 spherical chamber. Occasionally two or even three eggs are 

 enclosed in one mass, but always in separate compartments. 

 Vom Rath regards the egg-laying as a continuous uninter- 

 rupted process which follows in about three weeks or a 

 month after a single act of copulation. It would seem, how- 

 ever, that in G. limbata at least the laying is done at intervals, 

 with several intervening acts of copulation. After the laying 

 the female pays no further heed to them. The young Glomeris 

 make their way out of the case by eating a hole in it. In 

 consequence of this many authors regard the case as a source 

 of food for the young. This can only be an accidental use, 

 as the shell is often made of excrement that is little better 

 than earth plus a little glandular secretion. Comparison with 

 the Polydesmids will show that the case serves a much more 

 important economic purpose than the provision of a first meal 

 in surroundings where food is plentiful. 



Polydesmus complanatus. 



The breeding-period is similar to that of Glomeris, though 

 Fabre placed it in September. In this he was led astray by 

 the discovery of coupled pairs in autumn. Copulation may 

 take place in warm weather at any time of year, but no one 

 has ever found eggs except in spring and summer. 



The genital openings are on the third segment, and, unlike 

 Glome? is, the copulatory appendages of Polydesmus take the 

 place of a pair of legs on the seventh segment. The male 

 approaches the female from behind, and runs along the back 

 till the head is reached. Suddenly turning round towards 

 the ventral surface, he seizes the lower lip with his mandibles, 



