94 Messrs. C. B. Williams and P. A. Buxton on 



central core containing the eggs C, surrounded by a pro- 

 tective layer D, and separated from it, laterally and 

 ventrally, by a stout irregular wall F. The central part 

 is divided by transverse vertical lamellae G- into a number 

 of flat chambers, each containing a group of eggs. Each 

 chamber is roughly semicircular, being closed at the middle 

 line (I), and the chambers on each side alternate (III). 

 Each compartment communicates with the exterior by a 

 passage (A and B) leading from the eggs to the dorsum of 

 the ootheca, where it opens between the successive members 

 of a series of flaps H. Within each opening there is a 

 protective flap E, arranged as a valve, so that it can be 

 pushed aside from within but prevents entry from without. 

 The vertical divisions between the egg-chambers continue, 

 less stout in structure, across the outer protective layer D, 

 and are indicated on the exterior by a series of vertical 

 furrows on the sides of the ootheca M. A few chambers 

 at each end of the ootheca are without eggs, and act only 

 as protection. Giardina (1899, p. 296) considers the trans- 

 verse walls between the egg-chambers to consist of three 

 layers closely pressed together, but we could see no evidence 

 of this ; they tend to split in places, but quite irregularly. 



The whole ootheca is formed of a gumlike substance 

 secreted from large abdominal glands, which open into the 

 oviduct. This gum, which hardens on exposure to air 

 after being secreted, is partly vacuolated into a kind of 

 froth by the gonopophyses as it passes from the body. 

 That portion which goes to form the outer protective 

 layer is still more vacuolated afterwards. 



The construction of the first ootheca laid by the female 

 started about one o'clock in the afternoon, and by two 

 o'clock, when it was first observed, about one-quarter had 

 been completed. The insect was head downwards on the 

 perforated zinc side of the cage, and was so engrossed in 

 the process that, even when the cage was broken to pieces 

 in order to get a better view, it was not in any way dis- 

 turbed. The elytra were slightly raised and quite clear of 

 the ootheca, and only the very tip of the abdomen was 

 immersed in the froth, at certain times as far as the base 

 of the cerci, which, however, were always quite free and 

 were employed in feeling the surface under construction. 



The use of the elytra in the formation of the ootheca 

 has been affirmed and contradicted many times. There 

 is no doubt whatever that the ootheca can be constructed 



