1909.] ECTOPARASITES OF THE RED GROUSE, ilies 
two are sometimes completely fused, so that we only find 8 visible 
segments. 
There are certainly only 8 visible in Goniodes, although 
Nirmus has 9 complete segments. The last visible segment in 
the female is a slightly bilobed plate bearing no hairs; the anus 
opens just below it. In the male the plate is not bilobed; it is 
stouter and bears a number of backwardly projecting hairs. 
Each segment, except the last in the female, bears a number of 
hairs; the arrangement of these is shown in the figures 1, 2, & 3, 
Plate XXXV. 
The appendages are as follows :— 
I. The eyes.—Each eye is formed of a little aggregation of 
pigmented cells, the whole somewhat cup-shaped, and of an 
almost spherical transparent thickening of the cuticle, the lens. 
The eyes are situated close behind the thickened cavity from which 
the antenne arise (Pls. XXXV. & XXXVI. figs. 1, 2, 3, & 4). 
JJ. The antennze.—These arise from 2 deep hollow the chi- 
tinized walls of which are much thickened. The cavity practically 
conceals the proximal joint, which is broader than long; the 
second joint is the longest and is almost twice as long as its 
broadest part; the third, fourth, and fifth segments uniformly 
diminish in size, and the fifth or last bears at its end a number 
of bristles. The male is readily distinguished from the female 
by the fact that the third joint is produced into an inwardly 
directed process very like a thumb, and this gives the antennz a 
biramous appearance (Pls. XXXV. & XXXVI. figs. 1 & 4). 
The next three pairs of appendages are modified as mouth- 
parts, and in describing them we propose to mention certain 
median structures also connected with the mouth. 
The most remarkable feature of the under surface of the head 
of a Goniodes is a white cushiony area with the outline of a 
stout sausage, sometimes described as the “upper lip” or 
“labrum.” It is bounded anteriorly by a ridge of chitin which 
takes its origin on each side from the inner face of the strong 
apodeme already mentioned. This cushion is covered with a 
multitude of rugosities, giving it the appearance of the skin of 
a dog-fish. There is always a more or less well-marked crease 
or groove across the long axis of the cushion, and the part 
posterior to the crease is supported by two longitudinal bars of 
chitin just as the double banners Temperance reformers carry in 
their processions are supported by the poles (Pl. XXXVI. fig. 5). 
If one be watching the living Goniodes lying on its back on a 
slide, this cushion will be seen from time to time to swell up and 
scrape along the under surface of the cover-slip. Then it subsides 
again, possibly being pulled back by the numerous muscle-fibres 
which pass back from the anterior end of the head, and which 
appear to be inserted into the inner surface of the cushion. 
Along the posterior edge of the cushion is a small mobile mem- 
brane or lip which bears a moustache of eight hairs, shorter in 
Proc. Zoou. Soc.—1909, No. XXII. 21 
