300 WHEELER. (Vor. IIT. 
and becomes evenly continuous with the secretion which has 
before been spread over the back and the sides of the capsule by 
the white membrane. When the anterior end of the capsule is 
examined, the escutcheon-shaped vaginal opening is found to 
have left its impression even to the delicate wrinkles into which 
the surrounding cuticula was thrown by the closing of the ori- 
fice. This end of the capsule is white, gradually shading into 
the brown of the opposite end. 
The crista, a cord-like ridge running the full length of the 
dorsal surface of the capsule, is a thick-walled tube, either half 
of which is formed by the edge of the side walls of the capsule 
split into two laminz (Fig. 3 04, 0”). The rhythmical clasping of 
the three pairs of palpi, which guard the vaginal opening, is 
registered in an exquisite pattern on the inner face of either 
half of the crista. 
The canal is filled with a vacuolated substance (Fig. 3 ef) 
which at first sight resembles the yolk of the egg, but when 
examined more closely is seen to have quite a different struc- 
ture and origin. In the egg ready to leave its follicle the epi- 
thelium is much thickened at the germarium pole into a bicon- 
vex-lens-shaped cap (Fig. 4), the cells of which are not flat like 
those on the other portions of the egg, but long, columnar, and 
more or less curved. The two laminze of the chorion spread 
apart beneath this cap and dilate into a pear-shaped sac divided 
up into numerous polygonal chambers by delicate chitinous 
partitions (Fig. 4 4). While the egg is leaving the follicle, the 
epithelium at the lower pole is loosened from the chorion, and 
the egg protrudes into the oviduct. As it advances, the epithe- 
lium is rolled back and doubled up in folds till it is freed from 
the chorion as far as the cap. Then it breaks, letting the egg 
pass into the oviduct with the thick cap of cells firmly attached. 
The egg is-placed in the capsule, and the cap comes to lie in 
the crista, filling its lumen. The large nuclei degenerate, and 
soon entirely disappear, the protoplasm becomes dry and vacuo- 
lated, and finally transformed into the yolk-like mass described 
above. This substance probably serves as a cement to keep 
the lips of the crista in contact till separated by the emerging 
larvee. Thus a small portion of the follicular epithelium, that 
portion which corresponds to the nourishing cells in other 
insect ovaries, is deposited with the egg. To my knowledge 
