116 Bulletin de la Société Roijale Entomologique d'Egypte 
The height of the egg-cases is 4 mm. and is prae> 
tically constant; the width of the base is more variable 
but, in the great majority of the cases considered in 
this note, it is also 4 mm.; a few of the late egg-cases 
— even of fertilized females — are narrower, some 
not exceeding 3 mm. This is due to a deficiency in 
the amount of the foamy material available for the 
formation of the outer covering of the case. On the 
other hand some of the first egg-cases laid by unfer¬ 
tilized females have more of this substance than they 
really need and the width of the base may reach 
5 mm. As these exceptions all fall within the very 
large or the very small group, it is not necessary for 
the purposes of this note to consider the differences 
in the area of cross-sections involved. We shall there¬ 
fore consider only the length of the egg-cases. 
Owing to the difficulty of deciding exactly where 
the tail begins, without cutting the egg-cases, very 
exact measurements are rot possible. Fortunately they 
are unnecessary as will be seen from table IV. After 
measuring a number of egg-cases, I found that they 
fell conveniently into the five groups indicated in 
that table; a few fell near the border line of two 
groups and were placed in the smaller of the two, the 
tail being given the benefit of the doubt. 
Each egg-case was kept in a separate box until 
there was no further likelihood of emergence, those 
from which no young emerged until the middle of 
July 1918. During that period 17 were lost. Of the 
remainder, 3 o of the earliest were put together after 
hatching, but unfortunately they were not labelled. 
The remaining 290 were all labelled. 
