338 THE CANADIAN ENTOMOLOGIST 



small tube with dense walls, functions in the admission of air into 

 the egg chamber. Whether this is so or not I could not determine 

 in the few experiments I performed. Below the broad expanded 

 base of the spine 'is a narrow lunar-shaped opening (figs. 2 and 3). 

 This allows the entrance of water beneath the egg-case proper, and 

 through it the newly-hatched larva? escape. This outer sheet of 

 silk enveloping the egg-case is very thin and semi-transparent. 

 Through it one can readily observe the young larvae as they hatch 

 and crawl into this space before venturing out into the open pond. 



The eggs form a disk-like mass suspended from the roof of 

 the egg-case (PI. XXII, fig. 3.) They are all arranged vertically, 

 closely applied to each other and in a single layer. Above the 

 eggs the roof is composed of a considerable thickness of rather 

 loosely-woven silk, leaving comparatively large, open spaces. Each 

 egg measures 4 mm. long and about 1 mm. in diameter, yellow in 

 colour, and loosely wrapped in its own coat of silk. Although I 

 have examined these egg-cases carefully, I have never found any 

 water in the portion containing the eggs. It would seem as if the 

 open spaces in the loosely-woven silk and connected with the horn- 

 like process in front serve as a means of air supply for the de- 

 veloping embryos. The number of eggs in a single case is very 

 large, and it is not known how many egg-cases may be made by a 

 single female. In the two egg-cases counted there were 112 and 

 130 eggs, while Garman found 107 in the one counted by him. 



The young larvae on hatching do not immediately leave the 

 egg-case. On the evening of June 25th I saw quite a number of 

 the newly-hatched fellows crawl out into the space below the eggs, 

 but they did not venture further. Next morning this space was 

 literally swarming with them, so crowded that they could not 

 attack each other. Shortly after they began to emerge; slowly at 

 first and then more rapidly. Soon the small aquarium was a 

 seething mass of wriggling savages. They nipped at each other 

 fiercely, each shying off, but soon one got a death-grip. The suc- 

 cessful grip is directly back of the large head (fig. 29), for then the 

 larva is helpless, and the other little savages soon close in and 

 complete the killing. One is not much of a feast for over a 

 hundred hungry chaps, and the first taste is only the beginning. 

 After considerable manoeuvring, another is seized and the 



