upon the Leaf of a Plant belonging to the Order Ochnaceæ. 577 
The discovery of the exuviæ in some of them, in addition to a microscopic 
examination, placed it beyond all doubt that I had before me the production 
of an insect. 
Twenty or more individuals are produced on the same leaf (in that before 
me twenty-three), the upper surface of which is furnished with a strong shining 
cuticle. As soon as the presence of the grub has caused the tissue imme- 
diately around it to swell, and to detach itself above and below, by a sort of 
concentration, from the cuticle, there is an evident attempt, as it enlarges, 
exactly as in Æcidium cancellatum and other allied epiphytal Fungi, to burst 
indifferently through either surface, but, apparently, it is in general unable 
to overcome the superior resistance of the upper cuticle, though that is 
somewhat raised and occasionally a little ruptured, and consequently forces 
its way through the hypophyllous cuticle, splitting it into a few subacute 
laciniæ. 
Each gall is cylindrical, about a line long, and consists of two distinct sub- 
stances, the outer of which is dark brown, and evidently a continuation of the 
inner substance of the leaf; the inner much paler, thinner, shining and horny, 
as is indeed the case in many galls. The apex is strongly umbilicate with the 
border, which is formed of the outer coat, slightly expanded, and furnished 
with a few shallow, obtuse, distinct crenulations. At the bottom of the um- 
bilicus is a nipplelike operculum. The operculum is solid and formed of the 
outer coat, but is intimately connected with the top of the inner horny sac, 
which is very thin above, and thus forms a lid to it, which fits on exactly 
where the outer suddenly diverges from the inner coat, so that little resistance 
is offered to the egress of the insect, except that of the upper portion of the 
inner coat, which, as said above, is extremely thin, and, at the point where the 
operculum fits on, very brittle. There is sometimes a little punctiform de- 
pression at the top of the operculum, which is probably the scar of the punc- 
ture made by the ovipositor of the insect. Seventeen of the galls were already 
burst; and out of the remaining six, one only furnished an imperfect grub, 
and this being exceedingly light and dry, was unfortunately lost whilst the 
drawing was in progress. Several of the other galls had the remains of exuviz, 
but too imperfect to furnish any information. I am not aware that there is 
any instance on record of a gall bursting through the cuticle; and the oper- 
