190 Transactions.—Zoology. 
We are all familiar with the appearance of the outer shell or shield of 
the apple scale. The shield varies considerably in different genera: some- 
times it is round, sometimes long, sometimes white, sometimes brown, but 
it invariably exhibits, in some part or other of its extent, when taken from 
the adult female insect, the two pellicles which she has discharged in her 
earlier transformations. In my plate V., fig. la, is shown part of the 
shield of the apple scale, mounted to show the pellicles. In the shield of 
the male insect, in certain species, only one pellicle appears, the insect 
undergoing only one transformation before the pupa stage. 
The female insect, having arrived at her full growth, fills her shield with 
eggs. A figure of its appearance is given in plate V., fig. 15, for the apple 
scale. 
The young insect shows no sexual differences. It is oval in shape 
(plate V., fig. 1c), with six legs, two antenne, and two eyes. 
The female, discarding her first skin, throws off also at the same time 
all external organs except the mouth or rostrum. In the first pellicle 
attached to her shield the remains of the antenne may almost always be 
seen. The legs are not to be found, andI cannot say what becomes of 
them. The insect, thus debarrassed of her limbs and eyes, becomes only 
an inert mass. She remains thus for some time, merely feeding and grow- 
ing, still retaining an oval shape, as shown by the second pellicles in the 
shield. Throwing off this pellicle, she appears in her adult stage, a des- 
cription of which must be left till I come to each species, as they differ 
considerably. 
What I have just said as to the discarding of the limbs is, like every 
rule, subject to some exception. In one or two species, chiefly of the genus 
Mytilaspis, a pair of minute protuberances, which M. Signoret states are 
rudimentary antenne, are visible on the head. 
The adult female, whatever her shape, oval or round, is much cor- 
rugated, in fact made up of rolls of fat, with the exception of the head— 
which is usually smooth, and of the abdomen—which is peculiarly shaped 
and marked. The colour of the insect as a whole varies—being sometimes 
whitish, sometimes pale yellow, sometimes red. 
In all cases that I have observed the abdominal region is of a bright yellow 
colour, and it is from the markings of this portion of the body that the 
specific differences of the genera of Diaspide are taken. My plate V., fig. 
ld, gives the appearance of the abdomen of Mytilaspis pomorum, the 
apple scale, which I have taken as the type of the group. It will be seen 
that the corrugations of the body end a short distance from the posterior 
extremity, which has a curved outline, broken by numerous small lobes, 
“intermixed with scaly hairs, The anal opening is at what might be termed 
