STEUCTURE AND BIOLOGY OF SCHIZONEURA LANIGEEA. 661 
IV. GrENEEAL BoDY FoKM (PI. 38^ figs. 1, 2, and PI. 41, fig. 35). 
The body of the apterous vivipai-ous female is oval in 
outline. Its colour varies fi’om a dull brownish-purple to a 
richer plum shade, the legs, anteunse, and beak being slightly 
paler.^ It presents a well-marked segmentation into head, 
thorax and abdomen. The head of aphids, according to 
Huxley (1858, p. 230), consists hypothetically of six segments, 
but it is usually referred to as the first segment. The thorax 
consists of three segments, and the abdomen, theoretically, of 
eleven ; but the terminal segments of the body are consider- 
ably reduced and only nine abdominal segments are visible. 
The lateral margins of the abdomen are often Avell developed, 
forming a wrinkled border or connexivum. In fully fed 
gravid females however, the body is much distended, the 
dorsum being strongly convex, and the connexivum less 
pronounced. 
Completely covering the body is a flexible, chitinous 
cuticle or integument, which is stouter on the head and coxm. 
The head is strongly deflexed under the anterior end of 
the body, and is produced on its dorsal or anterior face as 
a pointed upper lip or labrum {Ibr.), which lies above the 
mouth parts. 
On its postero-ventral surface is developed the conspicuous 
beak or proboscis (pr.), which in repose, lies on the venter 
between the coxae. It has a well-defined longitudinal groove 
{1. g.) on its anterior face, in which lie the delicate, chitinous 
setae {md.), [mx.]. These structures, on account of their 
delicate, haii--like appearance, are generally known as the 
“setae.”- In the following description I shall refer to 
’ Wlien crushed between the fingers, a reddish blood-coloiu’ed fluid is 
squeezed out of the body, and hence this species is known to German 
authors as the Blutlaus. Sorby (1871, p. 351), who made some chemical 
observations on this colomlng matter, calls it “ aphidiene.” 
- The term “ setae ” means stiff hairs or bristles, and its application to 
these mandibular and maxillaiy stinctures in aphids is misleading. It 
is however, so extensively used in the literature that I have retained it 
throughout this paper. 
