66 Trans. Acad. Sct. of St. Louts 
These figures indicate that there is no appreciable dif- 
ference in the time required for the formation of the 
second, third or fourth egg case, and also that this inter- 
val is practically the same (except for a few cases) as 
the time elapsing between the last moult and the first 
oviposition, as shown on page 63. Both sexes were often 
kept together in the jars, and it is not known whether 
mating occurred more than once. The eggs were all 
fertile, but I suspect that these long lapses between egg 
cases are probably due to the maturation of the eggs, 
rather than a necessity of mating for each egg case. 
An interesting observation from the biological stand- 
point would be to test the fertility of the eggs in rela- 
tion to one or more matings. 
Period of incubation—The period during which egg 
cases were deposited extended from the latter part of 
May to the end of July. The period of incubation seems 
unusually long. At the time of the emergence of the 
nymphs, all leave the egg case at one time, instead of the 
alternative of the emergence covering a number of days 
for each case. The following data on the period of in- 
cubation were collected on egg cases deposited from May 
21st to June 11th: 
Number of Number of 
Days egg cases | Days egg cases 
45 8 52 6 
46 7 53 6 
47 3 34 1 
48 1 59 5 
49 1 56 4 
50 3 61 1 
_ 8 Total___-54 
