PROCEEPINGS OF THE PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
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used in trimming ladies’ dresses. The galls seen from 
above are round, not exceeding -J-inch in breadth, and 
in the centre there is a considerable circular depression. 
Seen from the side, they are flattened on the side next the 
leaf and slightly convex above. The surface is covered with 
fine silky shining brown hairs, directed downwards over 
the rounded sides. In section they are found to enclose a 
small lens-shaped cavity below the depression, and in this 
the larva lives. The galls are developed in autumn, fall to 
the ground and lie among the dead leaves all winter, and 
give birth to the asexual insects in the following spring. 
Neuroterus ostreus Hart, is pretty widely distributed in 
Scotland, especially in the southern districts ; but it can 
hardly be said to be anywhere abundant. The galls are 
situated on the midrib, or on the chief veins, seldom more 
than three or four occurring on a leaf. They seem to be 
restricted to the lower surface. They are oval, attached 
by one side, about 1-7 th-inch long when full-grown, and quite 
smooth and shining. At first they are greenish, afterwards 
becoming yellow, with numerous small dots of red or violet- 
red. Each gall is partially en closed at the base by two mem¬ 
branous lappets that seem to be the ruptured epiderm of 
the leaf-rib. The wall is not thick, but is very compact. 
The galls are formed in the latter part of summer, and in 
autumn they fall to the ground, where they lie all winter. 
The asexual insects emerge from November till next 
spring. 
Biorhiza renum Hart, is common wherever I have 
looked for it at the proper season. Owing to its small 
size, the gall is by no means conspicuous, nor does it 
continue long on the leaves. The galls appear in Septem¬ 
ber. For some time they remain very small, not so 
large as pinheads; but as they are usually found in masses 
of six or more on the veins of the lower surface, they may 
be detected without difficulty when looked for. After a 
time they enlarge to three or four times their former size, 
change from kidney-shaped to nearly globular form, and 
lose their former greenish hue, becoming nearly white. 
They fall to the ground, and the asexHal insects emerge 
during the winter, 
Spathegaster baccarum L. is the maker of the “ currant 
galls of the oak,” which must have been noticed frequently 
by every one during the month of May, hanging on the 
male catkins like bunches of currants, or, more commonly, 
growing on the leaves. In the latter situation they are 
fixed by a broad base, which projects through to the upper 
surface of the leaf, while the globular gall, frequently as 
large as a sloe, projects chiefly from the lower surface. 
Frequently two of the galls are more or less completely 
fused together. The surface of the gall is quite smooth, 
and is green with red or purplish-red irregular mottlings. 
They have a translucent appearance, like the red or white 
currants. The walls are relatively very thick, and are 
extremely full of sap; hence, after the escape of the insects, 
the galls shrivel up to a very small size. There is hardly 
any trace of a distinct inner wall. They are formed as soon 
as the leaves begin to burst out from the bud in spring. 
They grow rapidly, and in the course of a week or two have 
reached their full size. The insects emerge in June and 
July; and there are both males and females among them, 
Spathegaster tricolor Hart, has been found by Mr 
Cameron in various localities near Glasgow; but I have 
not myself seen it in the North of Scotland. The galls are 
spherical or nearly so, about l-5th-inch in diameter, 
covered sparingly with long slender simple white hairs, and 
rather fleshy in texture, with a moderately thick wall. 
They are formed in May, and the insects (males and fe¬ 
males) emerge in July. 
Spathegaster albipes Schenck. is recorded by Mr Came¬ 
ron thus “ I find it commonly around Glasgow. The 
very small size of the gall renders it easy to be overlooked ” 
(E.M.M., vol. xiii., p. 200). The galls are situated on 
the margin or on the midrib (causing distortion) of the leaf. 
They are oval, about l-12th-inch long by half as much 
in breadth, and attached by one side. At first they are 
slightly hairy, afterwards becoming naked, and are greenish 
in colour, passing into yellow. They are produced almost 
with the earliest appearance of the leaves ; and the insects 
(male and female) emerge in the end of May or in June. 
Spathegaster verrucosa Schlecht. is another of Mr Came¬ 
ron’s discoveries, he having found the galls in Mugdock 
Wood (Proc. N.H. Soe., Glasg., vol. v,, p. 158), on the 
leaf-buds and the young leaves. They are affixed to the 
veins or midrid, are spindle-shaped or clavate, end in a 
blunt tip, and may reach a size of 1 -5th-inch by l-10th- 
inch. The surface is smooth, bluish green, becoming 
greenish-yellow, with red markings, and is covered with 
bladdery simple hairs. The wall is relatively thin, and 
has no distinct hard inner layer. The galls are formed as 
the leaves appear; and the insects (male and female) 
emerge in the end of May or in June. 
Spathegaster vesicatrix Schlecht. is probably general in 
its distribution in Scotland, though as yet recorded only 
by myself for the North-east and Forres, and by Mr Came¬ 
ron for Glasgow. I have seen it around Perth and near 
Dumfries. The galls are sunk in the leaf, so that they are 
not at first readily recognised as galls. There is only a 
convexity on each surface of the leaf, enclosing a lens¬ 
shaped space in which the larva lies. The gall is cir¬ 
cular, not exceeding J-inch in diameter, with a small 
