6 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
body contain, as well as oil globules, masses of opaque granules, apparently 
of a calcareous nature. 
In addition to the fat body, certain very curious cells are seen free in the 
body cavity. On dissecting the abdomen, these are liberated and lie about 
on the slide, quite unconnected with the other tissues. They are oval or 
spindle-shaped, measuring 140 /u in length. At one or both poles they have 
a delicate spike-like process. They contain two nuclei, and possess a fairly 
resistant cuticle, which is left as a shrunken structure when the cell contents 
have been extruded. In spite of the parasitic like aspect of these cells, they 
appear to be normal tissue cells of the louse. Somewhat similar cells, 
though in less numbers, were found in dissection of a species of louse infest- 
ing calves. Certain groups of small, partially free, cells are also seen in the 
body cavity, especially near the terminal segments. The nature of these 
and the large cells noted above is not clear. 
Muscular system. — Powerful muscles ar? concerned with the pumping 
organ and the large antennae. These occupy much of the space in the 
head, which is not taken up by the large ganglia. The thorax is mainly 
muscular. The abdomen has certain small dorso-ventral muscle bundles, 
which, seen in optical section in the fresh louse, are conspicuous refractile 
bodies. A band of muscle passes along each side of the body, and is attached 
to each segment near the origin of the long hairs. In the male powerful 
muscles are seen in connection with the penis. 
Tracheal system. — Two large spiracles of oval shape are situated just 
behind the spiny area of the thorax. From these, and smaller abdominal 
stigmata, tracheae form loops with distributing branches for the tissues. The 
tracheae are not very large or numerous. 
Nervous system. — The ganglionic masses of the head are of great size. 
The thoracic ganglion is also a large and conspicuous object, especially in 
sections. 
The circulatory system. — There is a pulsating chamber beneath the 6th 
and 7th abdominal terga, from which a dorsal vessel, also pulsatile, passes 
forwards over the mid-gut. Muscle fibres of a peculiar nature pass outwards 
from the chamber to the body wall. 
Habitat. — Parasitic on the Indian field rat (Gerbillus indicus), chiefly in 
the region of the head and shoulders ; but to a less extent elsewhere. The 
lice are active in their habits, and evade capture, although the eyes are 
absent in both sexes. In this connection it may be interesting to add that 
their host is nocturnal in its habits and an extensive burrower. 
This species is related to Kcematopinus acanthopus, Burm. ; found on the 
European field vole (Arvicola sp.) and H. scutropteri, Osborne, of North 
America ; but it is easily separable from these by the greater number of hairs 
on the abdominal segments, by the form and character of the hind tarsi, and 
the structure of the genital armiture of the male. 
EXPLANATION OF THE PLATE 1 
Fig. i.— Male (ventral), X 75- 
Fig. 2.— Antennae of the male, X 150. 
Fig. 3-— I-eg ii of the male, X 150. 
Fig. 4.— Tarsus of leg iii of the male, x 150. 
Fig. 5.— Head of the female (ventral), X 75- 
Fig. 6.— Antennae of the female, x 150. 
Fig. 7-— Leg i of the female, X 150. 
Fig. S.— Anal segment of the female, X 75- 
