* 
192 Transactions.— Zoology. 
Having thus briefly enumerated some of the characters which are 
common to all the Diaspide, I proceed to particulars. 
The group is divisible into several genera, but I need now only mention 
those of which I have obtained specimens in this country. Considering the 
immense number of plants, imported or native, whether in greenhouses, 
gardens, or the bush, which are attacked by scale insects, and the multi- 
tudinous variations of form and markings which distinguish the individuals, 
it is likely that future research will discover, if not new families and genera, 
at any cate many new species. 
The genera known to me at present are the following :— 
1. Myritaspis. This includes the apple scale and many others. The 
- shield, or puparium, is elongated ; the two discarded pellicles are seen at 
the smaller end. 
2. Asprpiotus. Shield of the female round, or nearly so; that of the 
male somewhat oval; discarded pellicles in the centre. 
8. Draspts. Shield of the female round, as in the last genus; the dis- 
carded pellicles usually near the side ; shield af the male elongated. 
Subsection I.—Myrtinaspis, Linn. 
The females in many species of this genus, as a rule, resemble each 
other in form. The number and disposition of the groups of spinnerets 
offer a means of distinguishing the species. The males, in most cases, are 
unknown. 
1. Mytilaspis pomorum, the apple scale. 
Plate V., figs. 2a, b, c, d. 
This species is not indigenous. The shield, which may be seen cover- 
ing the trunks and branches of oür apple, pear, and other trees, is elongated, 
mussel-shaped, brown or grey (I have seen some white). It is open under- 
neath, adhering to the tree with its edges; it has considerable consistency ; 
length averaging 4'; inch, breadth nearly „y inch. The discarded pellicles 
are at its smaller end, and, when mounted in balsam, the rest of the shield 
is seen to be composed of transverse interlacing curved fibres. 
In the spring, a close inspection of a branch of apple tree will show a 
number of extremely minute yellowish specks intermingled with the adult 
puparia. These specks are the young of the insect, hatched and beginning 
to travel on their own account. Plate V., fig. 1c, shows the form at this 
stage. It is oval, flattish, yellow-coloured, with two antenne, each with 
six joints (of which the last is the longest); the antennz have longish hairs 
on each joint. The head is smooth, rather darker in colour than the body, 
with four hairs on its anterior edge. The body is corrugated, each corruga- 
tion having a spine. The anal extremity is yellow, with several hairs, of 
which two are of some length. The legs have short femora, tibie rather 
