140 Psyche [August 
both at the ends and middles; at WX they are joined only at the 
ends; at UV they are altogether free. As the plates of the egg 
chambers in one row have flaps which are of equal breadth on 
either side of the longitudinal center of the ootheca, and as this 
is also the case with the chambers in the other row (which are 
half a chamber’s depth behind or in advance) it follows that the 
flaps of the chambers on either side interlace. The lower edges 
of the two flaps forming an egg chamber are rigidly held on the 
outside of that row by two corresponding coverstrips; but the edge 
of the flap which comes across from the chamber of the opposite 
row and lies between the two former flaps is slightly within the full 
width and is left uncemented till a little lower down, and can thus be 
pushed slightly back by the emerging nymphs. ‘Thus on each side 
of the row of flaps the lower edge of each flap is held rigidly or is 
semi-free alternately. 
It may be added that some oothece are very small, having per- 
haps but six egg chambers; others have more than thirty, but the 
average length of an egg-case is about an inch, with about twenty- 
four chambers. 
EXPLANATION OF PLATE 8. 
Figure 1, 
A, external side view, part of the exterior casing formed by the cover- 
strips broken away, exposing two egg chambers in the near row. 
B, vertical section through longitudinal center. 
C, vertical section (on line m—n, Fig. 3) through two egg chambers in 
the far row. 
D, external side view of back end. 
ec, egg chambers in far row. 
ec,’ egg chambers in near row. 
cm, closing membrane. 
FIGURE 2. 
A’, external top view. 
cp, cover-plate. 
B’, external top view, the flaps cut away as at UV. 
C’, top view, outer casing removed, flaps cut away as at WX. 
D‘, top view, outer casing removed, flaps cut away as at YZ. 
E', horizontal sections (on line Q—R, Fig. 3) through egg chambers. 
e, last small plate forming rough chamber without eggs. 
B, cover-plate. 
