166 Proceedings of the Royal Physical Society. 
the fork or false spiculum gastrale, the ring (the “gabel” of the German 
entomologists), and the sheath. 
The fork (Fig. 8a), as its name indicates, is a long chitinous rod 
diverging at its posterior end into two short branches. & 
The ring (Fig. 8) is a circular band of chitin encircling the bulb 
and sheath of the penis. It extends anteriorly as the anterior process, and 
posteriorly as the two posterior processes. These latter are finer than 
the first and bear a number of bristles. =a 
Sati 
The sheath (Fig. 8c.) consists of a fine plate of chitin, the edges of SAN 
which overlap and partly enclose the ejaculatory duct. It extends anteriorly 
into two fine rods, the femora, which are attached to the ring and fork by 
muscle. Towards the base of the sheath two small plates arise from either 
side and serve further to hold the ejaculatory duct in position. At the 
posterior end of the sheath a few fine bristles occur. The sheath is the 
only portion of the penis exserted in copulation. In Fig. 6 the chitinous 
parts of the penis are viewed from the side; in Fig. 8 they are separated 
and viewed ventrally, the sheath in the same figure is also shown in its 
dorsal aspect to the right. 
Figure 9 is a diagrammatic sketch showing the reproductive organs, 
or rather part of them, in situ, in both sexes, 
The organs in both sexes extend from the fourth to the eighth 
abdominal segments. 
THE BIOLOGICAL SIGNIFICANCE OF THE REN ODS Ly ORGANS. 
It has been said that the development of the reproductive organs of 
an insect, whose life in the imago state is a long one, may be of great 
importance as a guide to the main facts in the life-history of that insect. 3 
This is most true of the reproductive organs in the female. 
I have examined the organs of the male Hylobiws immediately on 
pupation, and after five months had elapsed since pupation, and except 
that the sperm sacs and diverticula were small and undeveloped, the 
immature weevil differs but little from the mature one. With the female, 
however, the difference in development of the ovaries and the seminal 
pouch is very distinct. | 
In the month of April of this year I obtained a number of pup of 
Hylobius, and placed them, still in their pupal chambers, in a large breeding 
cage. I further planted several young Scots pine trees in the cage as food for 
them. In a week or two they emerged and commenced feeding. I left them 
untouched till the month of August, when I examined several. The ovaries 
were as shown in Fig. 1. Ova were present in the egg-tubes, and the 
