280 Prof. L. C. Miall and Mr. T. H. Taylor on the 
segments. A pair of scoop-like plates, situated one on 
either side of the external aperture, perhaps serve to 
direct the egg as it emerges from the uterus. The uterus 
receives on its dorsal aspect the ducts of the receptacula 
seminis and of the gluten-glands. Both these organs are 
paired, and the ducts are lined by a chitinous intima which 
in the case of the ducts of the gluten-glands is spirally 
wound. Where they join the uterus the muscular wall 
of the latter is considerably thickened both dorsally and 
ventrally, giving rise to a conspicuous body of tissue lying 
in the 7th segment. Imbedded in the ventral portion 
of this muscular tissue occurs an unpaired hemispherical 
sac (d, figs. 18, 15, 18), which communicates by a short 
duct with the cavity of the uterus. The walls of both the 
sac and the duct are strongly chitinous. The floor of the 
sac as seen in sections strongly arches into the cavity, but 
as it is provided with muscles it can probably also be 
depressed ; we are unable to explain the function of this 
organ. Behind this special muscular region the uterus is 
thin-walled and much elongated to permit of the extension 
of the ovipositor. 
VI. EaG-LAYING AND Eaas. 
The eegs of the holly-fly are laid in June. At this 
time the young leaves are being put forth, while those of 
the past season are turning yellow. Some six or eight 
leaves are borne on each young shoot; the lower ones are 
the first to mature, and for about three weeks there is a 
constant succession of leaves fit for the operation of egg- 
laying. 
On examining holly-leaves at almost any time of the 
year a number of pits will often be remarked on both the 
upper and the lower surface. These first appear when the 
leaves are young and tender, but they persist in the fully- 
developed leaf without increasing in number. We used to 
think that these pits were caused by the spines of the old 
leaves, which pricked the young leaves at times of high 
wind, but we have now been led to adopt a different 
explanation. The pits do not actually perforate the leaf- 
blade; they commonly enter but do not pass through the 
mesophyll. Holly-trees which are not infested by flies do 
not show pits on the leaves, but those which are much 
blistered are also much pitted, Moreover we have seen 
