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III. — On a Species of Acarus of the genus Cheijletus, believed to 
he new. By A. D. Michael, F.K.M.S. 
{Read before the Hoyal Microscopical Society, May 1, 1878.) 
Plate VI. 
In the latter part of December, 1877, being on a visit -to some 
friends near Tam worth, Warwickshire, I found, by sweeping the 
walls of their beer-cellar, a tolerably plentiful supply of that 
interesting and beautiful acarid Glyciphagus palmifer, which had 
not before been found in Britain (and which I have announced 
elsewhere). I was at first occupied with Palmifer, but soon dis- 
covered that there was a predatory mite feeding upon them. A 
short inspection satisfied me that it belonged to the genus Cheyletus, 
and I soon saw that it was not any species that I was acquainted 
with. Subsequent search (as far as I have been able to carry it) 
has entirely failed to discover any record of the species, which I 
therefore presume to be new, although it is quite possible that 
some one may have observed it whose record I have not found. 
The state of our knowledge and bibliography as to Cheyletus 
seems to be as follows : — 
Latreille * * * § first mentioned, named, and described the genus. 
Schrankf mentions; Duges does not. 
KochJ gives it, and treats of the generic characters and 
habits ; and describes and figures five species in a manner sufficient 
for identification. He does not in any way deal with the sexes, 
nor with the larval or pupal states. His species are CK. eruditus 
(and casalis, which he regards as a variety) ; Ch. venustissimus 
(which I have dealt with below ) ; Ch. hirundinis, and Ch. margi- 
natus. 
Gervais § gives Eruditus and Marginatus only, and practically 
simply refers to Koch. 
Guerin |1 also copies Koch. 
LaboulbenelT mentions a species which he calls Mericourti, of 
DESCRIPTION OF PLATE VI. 
Cheyletus flahellifer. 
Fig. 1. — Upper side of female x about 125. 
Fig. 2. — Under side of female X about 125. a. One of the main tracheal 
trunks, h. Palpus, c. Lateral mammillary process, d. Anus. 
Fig. 3. — One of the fan-shaped hairs highly magnified. 
* ‘ Histoire naturelle des Crustaces et des Insectes,’ viii. 54. 
t ‘Euumeratio Insect. Aust.,’ 1058, pi. xi. 
if ‘ Deutschlauds Crustaceen, Arachniden, &c.,’ Regensburg, 1839, Heft xxiii. 
‘ Ubersicht die Arachnidensystems, &c.’ 
§ ‘ Hist. Nat. des Insectes-Apteres,’ Walkenaer and Gervais, vol. iii. p. 164. 
II ‘ Iconogr. Reg. Anim. Arachnides,’ pi. v. f. 8. 
4 ‘Ann. Soc. Ent. Fr.,’ 1851. 
