SOME PARASITIC ACARI. 
405 
GfotSTIOMERUS* MUSCUL1NUS, 1 IOY. gen. et sp. (PI. XXVI. fig. 9.) 
mm. 
Length about ‘155 
Breadth about '105 
Length of legs (all pairs) about '035 
Colour . — Semitransparent white. 
Texture . — Much that of the ordinary Sarcoptidse, i. e. smooth 
and leathery, not polished. The skin is marked more or less 
with excessively fine wrinkles or striations, so fine that they are 
very difficult to see. 
Form Sfc . — Body almost oblong, but somewhat narrower poste- 
riorly than anteriorly ; there is not any clear demarcation between 
cephalothorax and abdomen. The rostrum projects, but is bluntish; 
a pair of mandibles may sometimes be seen projecting from the 
mouth-opening. The rostrum bears a pair of fine hairs. The 
body is much compressed dorso-ventrally, and is divided into 
four lobes on each side, the hind lobe showing a slight tendency 
to be bifid. On the posterior margin there is a slight indenta- 
tion above the anus, which is almost terminal, but slightly on the 
ventral surface. Prom the hind margin spring a pair of long 
hairs directed backward, they are fully two thirds of the length 
of the body ; immediately below them are another pair of similar 
hairs proceeding from lobes on the ventral surface ; as this under 
pair is entirely concealed by the upper pair, when viewed from 
above, it is not shown in the figure. The legs are short, and are 
the great peculiarity of the creature; they are all alike and all 
directed forward, the fourth pair usually more so than is shown 
in the figure, where they are spread out. They consist of five 
joints ; the femur is very large and singular in shape, it projects 
beyond the body and bends suddenly at rather less than a right 
angle, so as to form an advancing corner which completely alters 
the direction of the leg. The more distal joints become gradually 
smaller ; the tarsus is terminated by a small claw, smaller in pro- 
portion than can be shown in a drawing the size of fig. 9, and 
there is another small chitinous projection close to it which may 
be regarded as a mere peg or a second claw ; I am inclined to 
look on it in the former light. There are hairs on the underside 
of each joint of the leg and one or more on the upperside of 
* yw via, an angle; /xjjpos, the thigh. 
