Paes General Notes. [March, 
whose abdomen is slightly compressed. The abdomen of the 
female is rounded. The wings of these insects and of the winged 
forms of Aphides are used chiefly as parachutes. The coxa of 
the limbs coalesce with the thorax, and the tarsi are two-jointed, 
bearing a pair of terminal claws. The hind-limbs are specialized 
for springing. The first abdominal somite of both sexes is added 
| to the metathorax to enlarge the springing-gear; the second 
abdominal somite forms a short stalk for the abdomen, and the 
] terminal abdominal somites are so modified as to have misled 
the systematists. In the male the tenth somite seems to be in- 
serted on the eighth, as the ninth has only its ventral part devel- 
oped and ends the abdomen, whilst the tenth, bearing the anus 
and penis, is reverted dorsad. In the female the ninth somite 1s 
discernible only by its appendages, and the tenth isa roofing 
dorsal plate (the upper genital dorsal plate of Low) bearing in its 
center the anus fringed by wax-glands. Thus in both sexes the 
is typical number of ten somites can be found. 
ne The circum-anal wax-glands are in the larve of both sexes; 
and wax-glands producing wax-fibrils are present on other parts. 
Wax-particles sometimes cover the larvae, protecting the back 
from excrementitious matter. Some larve (Psyllopsis) have 
spear-shaped wax-hairs ; the larva of Trioza has a marginal row 
: of leaf-like wax-plates. All the wax-hairs arise like chitinous 
oe hairs from large hypodermal cells, which have vacuoles presuma- 
bly filled with the secretion-fluid. 
= The stigmas of the tracheal system are denticulated on each 
= side, and have a self-acting closing apparatus (not as described 
~ by Landois). They have a short muscle on the ventral side, 
=- ~ so connected with the dorso-ventral muscles of the body that on 
the contraction of these muscles the stigmatic muscle contracts 
and opens the valve. This is probably for expiration. Inspira- 
tion is effected by the mere elasticity of the trachea, and the 
_ stigmatic valve closes by its own elasticity. The will of the in- 
= sect does not control these movements. J 
-The xervous-system and sense-organs are here treated relativel 
to insects in general, and much new light is cast on the subjec 
of the insect’s psychology. The brain of the Psyllide is rather 
large, having a middle lobe and two lateral lobes, the latter send- 
ing off the optic nerves (Figs. 3, 4). 
a 
; ing a central medullary system and a peripheral layer of a cortex 
Pats Thus I render Vorderkopf; “ procephalic-lobes” is inaccurate, as the part is "e 
_ paired; the term “ forehead ” is preoccupied.—G. M. i 
_ 
