350 THE GROUSE IN HEALTH AND IN DISEASE 



cheese. The head of the female is somewhat broader and shorter than that of the 

 male, and is produced at the posterior-lateral region into a much more 

 prominent angle. In both male and female the angle bears a spine and 

 a long hair. The anterior margin of the head is bounded by a thick rim of chitin, 

 beneath which is a layer of granular protoplasm with a few nuclei, the hypodermis. 

 At intervals the chitin is pierced by narrow channels, into which the hypodermis 

 extends, and the chitin bears at the outer end of each of these channels a short 

 sensory hair. 



There is no neck, but the first segment of the prothorax is only about one-half 

 the width of the head. The mesonotum is fused with the metanotum, and the 

 thorax appears to have but two segments. There is, again, no waist or constriction 

 between the thorax and the abdomen, but the segments from the first thoracic to 

 the second or third abdominal gradually and uniformly widen, and then as 

 unifoi'mly diminish in width until the last. 



According to Sharp ^ the Mallophaga have from eight to nine abdominal 

 segments, and according to Railliet ^ the family in which he places Goniodes has 

 nine ; but he remarks that the last two are sometimes completely fused, so that 

 we only find eight visible segments. 



There are certainly only eight visible in Goniodes, although Nirmus has nine 

 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 (PI. Liii., 

 Figs. 1 and 2). 



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 antennae arise. 



II. The Antenncp. — These arise from a deep hollow, the chitinised 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 



' "Cambridge Natural History," vol. v. Insects, i. London, 1895. 

 " " Traite de Zoologie Medicals et Agricole," 2nd edn. Paris, 1895. 



