340 TWO SPECIES OF PARASITIC MITES. 
forwards for a considerable distance to articulate with the epimera. 
The second joint is large, with a long and strongly curved outer and 
a short inner margin. On the outer side, but rather towards the 
dorsal surface of this joint, three small tubercles are present, bearing 
at their ends as many short bristly hairs. These are most strongly 
developed on the first and fourth legs, not being so conspicuous on 
the second and third. The third joint is smaller and more nearly 
round, though somewhat longer on its inner than on its outer border. 
On this latter border there is a short tubercle and spine present on 
the first leg, and a pair of blunt spineless tubercles on the fourth. 
Articulating with the distal end of the third joint is the fourth joint 
or tarsus, which at its proximal end is comparatively narrow, but 
after a short distance it suddenly increases to about double its 
original breadth, forming on the inner side of the first leg a back- 
wardly projecting spine, which, however, is not present in the other 
extremities. After thus enlarging the tarsus does not again contract, 
but continues of about the same size to the end of the joint, when it 
is sharply truncated, the end being straight or even slightly incurved. 
In this emargination, but rather towards the dorsal surface of the 
joint, a short blunt spine takes its origin. On the same joint, 
but on the extreme outer angle, there is also present a rather 
strong, slightly curved claw, of about the same length as the spine 
and with it giving to the leg the appearance of being terminated by 
two claws. Besides the spine and claw the tarsus is armed with 
two bristles, one on the inner and one on the outer side. 
Situated immediately under the thin transparent epidermis, and 
imbedded in the tissues of the body, the epimers, which are com- 
posed of strips of light-brown coloured chitin, extend from the 
anterior angle of the base of the legs towards the middle line of the 
body, and form with the small pieces of chitin behind the rostrum 
-the framework or skeleton of the trunk. Their principal functions are 
to serve as supports for the legs and to form points of attachment for 
the muscles which move them. Those of the anterior pair of legs 
arise on each side of the rostrum and close to it, and run backwards 
and inwards for about one-fourth the length of the body, not meeting 
to form a point, however, as in Sarcoptes minor, but turning sharply 
outwards and ending abruptly. Those of the second, third and 
fourth legs are also each of them present as detached bands. The 
