Séance du 16 Avril 192â 
137 
On examining the ligures given for the unfer¬ 
tilized females it is at once obvious that the irre¬ 
gularities are few and relatively much smaller than 
those shown in table X. Even those which are the 
largest are more apparent than real in most cases. 
The nth egg-case of N° 65 was laid on the 8th of Oc¬ 
tober, 17 days after the previous one. The i 3 th egg- 
case of N° 64 laid on the same day and 10 days after 
the twelth also* hatched more quickly than was to be 
expected. The intervals between ovipositions are 
exceptionally long in both cases and other egg-cases 
laid bv different females about the same date show the 
same tendency, though to a smaller extent. It is there¬ 
fore highly probable that these irregularities are due 
to changes in the weather at that time. Other apparent 
irregularities, of which the second egg-case of N° 68 
is the most obvious, are due to the fact that emergences 
occurred on several days. Young hatched from the first 
egg-case of N° 68 on the 21st, the 22nd and the 23rd 
day; from the second egg-case on the 22nd, the 24th 
and the 26th day; and from the third egg-case on the 
2 3 rd and the 24th day, so that the difference is not 
nearly as large as it would appear from the table. 
In comparing the incubation period for fertilized 
and unfertilized egg-cases, it must be remembered that 
the latter were laid later than the former so that the 
difference is not as great as a casual glance at the table 
would lead us to suppose. There is however a real 
difference amounting to 2 or 3 days in July and August. 
Thus we see that the incubation period is longer for 
egg-cases laid by unfertilized females, even at the most 
favourable time of year. 
