COCKROACHES, ETC. 153 



further protection they are closed at the top by a 

 tightly fitting lid the operculum, on which is generally 

 situated a little knob known as the capitulutn. It is 

 probable that this knob is itself nothing more than 

 an imperfectly developed egg, formed beside and sub- 

 sequently attached to the true egg in the ovarian tube 

 of the mother. There is, indeed, some evidence to 

 show that at one period of development the operculum, 

 too, is an imperfectly developed egg, so that the egg 

 as laid may be really a compound structure consist- 

 ing of one perfectly developed and two imperfectly 

 developed eggs, the latter being modified to form a 

 capitulum and an operculum. 1 



Not the least interesting feature of Phasmid eggs is 

 a peculiar sculpturing on the egg-shell, the hilar area 

 and hilar scar, resembling very closely similar struc- 

 tures on some seeds ; in such eggs as I have investi- 

 gated the embryo lies with the head just under the 

 operculum and the ventral surface under the hilar 

 area. The form of the egg varies greatly, and it is 

 possible to discriminate between closely allied species 

 by the well-marked differences that the eggs present. 

 Eurycnema herculanea, a large species that I kept in 

 captivity for some time, has a large smooth oval egg, 

 greyish in colour, with a spherical yellow capitulum. 

 Lonchodes uniformis lays a small dark-brown egg with 

 an orange capitulum shaped like the tuft on a goose- 

 berry. Sipyloidea sp. has a long pointed egg with 

 sculptured and rugose surface, and the capitulum is 

 long and pointed. The eggs of the Ascepasmince are 

 very peculiar, for they are exactly like the seeds of a 



1 Sharp, "Account of the Phasmidae," etc., in Willey's Zoological 

 Results, etc., Cambr., 1902, p. 75. 



