On a Species of Acarus, <&c. By A. B. Michael. 137 
ordinary bristles, along each side of the ventral surface, some way 
within the edge, pointing directly downwards, but not touching the 
ground. 
The vulva is very small and difficult to make out ; it is placed 
about the middle of the body, between the second and third pairs of 
legs, as in the Sarcoptidae. I am not at present able to say any- 
thing with certainty as to the male organ, or indeed the male at all ; 
I hope to do so hereafter, as I am still breeding the creature. 
1 have mentioned that I found the species in a dark cellar 
feeding on Glyciphagus palmifer. It is impossible to avoid being 
struck by the resemblance of these hairs to the leaf-like hairs of 
Palmifer itself, or to refrain from asking the reason of so singular a 
coincidence in such an unusual peculiarity ; and whether it may 
not possibly be an instance of mimicry useful to the Cheyletus, 
which, as far as we know, is without eyes, and which certainly lies 
in wait for its prey, making it less likely to be observed by the 
Gflyciphagus or other mites, and giving it a better chance of securing 
food ; of course it would be entirely premature to express this as 
more than a possibility until it is seen whether this species accom- 
panies Palmifer in other instances besides the present ; and with 
regard to the absence of visible eyes, I cannot help thinking that 
the Cheyleti have some sense of sight ; at all events they are 
sensitive to light, and one cannot watch them without coming to 
this conclusion. 
This species does not, as far as I have seen, proceed with the 
jumping action of Eruditus, but walks in a steady, determined 
manner, with the rostrum pointed straight forward and the palpi 
extended ; when actually seizing another mite it makes a short 
spring upon it. 
The tarsus is held perpendicularly, and the front pair of legs 
appear to act as true legs, and bear their share of the weight 
(unlike G. venustissimus). Nothing could be more ferocious 
than this mite ; the instant it comes across another mite it seizes 
it with its palpi by any part which happens to be nearest, and 
then either plunges its mandibles into it at once, or retreats 
backwards, dragging its captive until it dies, when it is quickly 
sucked dry ; the sucking action may sometimes be distinctly seen, 
and the contents of the prey traced down the tube formed. by the 
mandibles (or maxillae), and into the gullet of the Cheyletus. Its 
own species does not come amiss to it, and when I put together 
what I hoped were male and female, the stronger immediately 
killed the weaker and eat it. 
The female lays her eggs in a little heap and spins a thick web 
over them, on which she stands, coming off to feed ; the eggs are 
laid under some cover, and not in the open. I first detected the 
eggs on 1 7th of March, at which time they were not yet covered 
