146 
Transactions of the Society. 
In 1876 Megnin"*^ described and figured a creature under the 
name of U. vegetans; his description is so slight, that it is not 
possible to make any use of it. There is, however, a large and well- 
drawn plate, which shows a species without any claws or suckers to 
the first pair of legs. I am not aware that any other acarologist has 
found any creature which really corresponds in all respects to Megnin’s 
U. vegetans, the known species in which the same shape exists having 
claws and suckers on the first pair of legs. 
In 1881 Haller t asserted that Kramer’s TJ. ovalis was really 
the U. vegeta7is of de Geer. In 1882 Kramer replied, pointing out 
that his U. ovalis could not be identical with U. vegetans, because 
ovalis had suckers and claws to the first leg, and a genital plate 
(female) of a different shape. This is undoubtedly true if Megnin’s 
figure be taken to represent the true TJ. vegetans of de Geer, but I 
am not aware of anything to show that it does, and as others do not 
find what Megnin has drawn, it seems unlikely that it can have 
been de Geer’s species. It seems to me far more probable, as Haller 
supposed, that Kramer’s ovalis is the original vegetans ; at all events, 
in my opinion it is not Koch’s ovalis, and therefore if it be not 
vegetans it is nameless. If Hr. Kramer likes to treat it as being so, 
and to give it a new name, I am not wedded to the idea of its being 
vegetans, and should readily follow him ; in the meantime I call it 
TJ. vegetans, and I think that that name is probably correct ; at any 
rate, for the identification of the species called vegetans in this paper 
I refer to Hr. Kramer’s ovalis. It is as well to state that all my 
specimens of this species for the present investigation come from the 
nest of one of the wild social bees (a Bombus). I have frequently 
obtained the species elsewhere, but not in such abundance. 
Anatomy. 
Uropocla ovalis Koch. 
If an adult female Uropoda ovalis be laid on its back the 
large genital plate (epigynum of Berlese) will at once be conspicuous, 
exactly filling up the genital opening in the ventral plate. The form 
of this genital plate, which is a good specific character in Uropoda, 
may be judged of from plate IV. fig. 9. It will be seen that at its 
anterior termination, in the median line, is a bifid projection, like a 
two-pronged fork ; one prong of the fork is usually a little longer 
than the other. This projection is shown on a large scale in fig. 10. 
It is composed of clear, almost colourless chitin, while the rest of the 
genital plate is dark, and is received in a very slight depression of the 
ventral plate. It springs from the extreme ventral edge of the 
genital plate, and is not nearly as thick as the edge of that plate ; 
thus, although the genital plate enters the genital opening, and forms 
Op. cit. 
t Op. cit. 
