A Species of Acarus neiv to Britain. By A. D. Michael, 315 
much above half the length of the second. The fourth joint * is 
nearly as long as the second, and has the inner side of the posterior 
articulation projecting. The tarsus has a slight shoulder a little 
beyond the articulation, from this point it narrows in and becomes 
very fine ; the tarsus is the longest joint of the leg ; the tarsal 
sucker of this particular leg is small and fine, and the claw very 
small and difficult to make out. 
The use of this first pair of legs, and the distribution of the 
hairs on all the legs, are mentioned below. 
The second, third, and fourth pairs of legs, although longer than 
in the last species, do not vary from the usual type of the genus 
sufficiently to render it necessary to describe them. The sucker 
and claw and its supports are given in the drawing (Plate XVI., 
Fig. 4). 
There is a row of seven or eight strong hairs on the upper side 
of the body, a little within the edge, the first three near together ; 
each coxa bears a strong short curved hair pointing downwards and 
towards the foot. The first pair of legs have on the second joint 
two longer straight hairs a little beyond the middle, one on the 
upper and one on the under side ; on the third joint two similar on 
the upper side, a little before the middle ; on the fourth joint 
two similar at the commencement on the outer and upper side, 
and one short one on the hinder and under side, one short 
and one long about the middle of the joint, and one very long 
strong one on the upper and outer front end of the same joint, this 
is the longest and strongest hair on the creature ; on the tarsus 
there is a similar hair, not quite so long as the last, springing from 
the upper surface at the before-mentioned shoulder. All these 
hairs are conspicuously imbricated, like those of the Indian bat ; on 
each side of the point of the tarsus is a long strong hair, and in the 
centre is a shorter and finer one ; these hairs are closely jointed or 
ringed, but are not imbricated. 
The second pair of legs have a pair of hairs on the third joint, 
and two pairs on the fourth joint, all imbricated ; one small one 
half-way down the tarsus, and two pairs at the extreme end, all 
small and plain. The third pair of legs have a pair of hairs, and 
the fourth pair of legs one hair on the second joint, the hairs on the 
remaining joints being like those of the second pair of legs. 
The palpi in this species are without teeth on the falces, other- 
wise like the last species but slighter (Plate XVI., Fig. 2). 
It is well known that in the acari the first pair of legs are 
modified palpi, and M. Eobin has remarked that in some instances 
they appear not entirely to have lost the office of organs of touch ; 
* This joint is called the tibia by Nicolet. Robin rejects this name, and 
calls it “ la jambe,” following Savigny in reserving tibia for the lower half, 
where this joint is divided into two shorter ones. 
z 2 
