109 
RITTERIA NEMORUM KOCH. 
C. F. GEORGE, M.R.C.S., 
Kirton-in-Lindsey. 
(PLATE VII.). 
TuIs mite is one of the most interesting as well as the most 
abundant and most widely distributed of all the Rhyncholo- 
phidze I have met with. Individual specimens differ consider- 
ably in appearance from each other in size, shape, and colour 
when alive, or when long preserved or compressed, hence the 
necessity of examining their structure before deciding their 
specific names. I have fortunately been able to supply Mr. 
Soar with a living and rather fine and typical example of 
Ritterra nemorum, and he has made a good drawing of this 
individual. The representation of the wrinkles is a rather 
difficult matter, the creatures having the power as well as the 
habit of altering them at will. This habit is also to be observed 
in other members of the Velvet mites. 
With regard to its anatomy, in The Naturalist, for May, 
1907, page 180, is a figure of the mite (by mistake named 
Erythreus) and also a good enlarged figure of the mandibles 
and palpi. The crista is rather difficult to make out, especially 
in the living mite, in consequence of the number and position 
of the rather short, thick, and dark papillz in its neighbourhood. 
The upper part of it is indicated by the round mark seen in 
the figure on the anterior and central part of the cephalothorax. 
I have, however, been able to dissect it sufficiently for Mr. 
Soar to make a much enlarged drawing (see Fig. A). It 
consists of a chitinous rod, with a more or less oval form of 
loop at either end, the anterior one being the larger. With- 
in these loops, but on a higher level, there are two stigmata, 
each furnished with a tactile hair projecting obliquely outwards 
(the posterior ones only are shown in the figure). The whole is 
placed on a wider and irregularly broader chitinous plate. 
It will be observed that the crista differs somewhat from any one 
of those figured in The Naturalist for May, I9gII, page 200. 
This fact seems to indicate the importance of examining this 
structure in all the Trombidiide. Lamarck, in his Azstoire 
Naturelle des Sans-Vertébrés, published in 1818, divided the 
Acari into those having six feet and those having eight feet. 
The six feeted ones into three families (1) Astoma; (2) Leptus 
and (3) Caris. Since Lamarck’s time these six-feeted mites have 
been proved to be only the larval forms of mature mites. In 
the proceedings of the Royal Physical Society of Edinburgh, 
for 1910, Vol. XVIII:, page roo-roz, XII.,* will be found 
* Note on Leptus phalangu and Leptus autumnalis and their parent 
earthmites by William Evans, F.R.S.E. 
1913 Feb. ‘1. 
