The Early Development of Julus Terrestris.^ 



By 



F. Cr* Heafhcote, m.A., 



Trinity College, Cambridge. 



With Plates XXII & XXIII. 



My investigations, the results of which are contained in the 

 following paper, were begun in June, 1882. I collected a 

 number of Chilognatha and kept them in glass jars, the bot- 

 toms of which were covered with damp earth. I soon found 

 that Julus terrestris^ was the species best suited for my 

 purpose, as though the eggs presented some difficulties not 

 present in the eggs of other species, yet they were of a conve- 

 nient size and were easily to be procured in great numbers. 



I fed the animals on sliced apples and occasionally on green 

 leaves, and this diet seemed to suit them well, for I never failed 

 to get several clumps of eggs in the breeding season, though 

 it is only this summer that I succeeded in getting them in any 

 number. The breeding season of these animals lasts from the 

 end of May till the end of August, though the weather has a 

 considerable influence on the time when they begin and leave 

 off breeding. I have observed copulation, which takes place 

 exactly as described by Cuvier (' Kegne animal,' 3rd edit., 

 1836, vol. ii, p. 330). I was unable to determine how long a 

 time elapses after copulation before the eggs are laid, but believe 

 it to be short. About four days before laying her eggs the 



' The numbers in brackets in the text refer to the list of papers at the end. 

 ' The species was kindly identified for me by Mr. T. D. Gibson Carmichael, 

 F.L.S., as Julus terrestris, Leach. 



