JOURNAL 
OF THE 
ROYAL MICROSCOPICAL SOCIETY. 
DECEMBER, 1878. 
I. — On a Species of Acar us, believed to he new to Britain. 
By A. D. Michael, F.R.M.S. 
{Read before the Royal Microscopical Society, Is^ May and iZth 
December, 1878.) 
Plate XVI. 
Cheijletus venustissimus. 
In the beginning of January last (1878) I found this species, 
which I believe has not hitherto been detected in Britain,* in a 
stable ; near Tam worth I noticed one or two minute red specks 
running rapidly over the fodder. I secured three or four for 
examination, and I then ascertained that it was the Cheyletus 
venustissimus of Koch ;t that author, in his work published in 
1839, describes and figures the species in a manner suflicient for 
identification, although somewhat wanting in detail ; he states that 
it was then found in the neighbourhood of Regensburg and in 
Rhenish Bavaria, and was somewhat rare. 
The species is not noticed by Walckenaer and Gervais, and I am 
not aware that any subsequent author has noticed it, except by 
stating that Koch gives it as one of the genus ; as Koch’s notice 
is not very full and does not mention the larva, pupa, &c., a 
description may possibly be acceptable. 
EXPLANATION OF THE PLATE. 
Cheijletus venustissimus. 
Fig 1. — Umlcr side of female x about 70 (the imbrication of the hairs is some- 
what exaggerated) ; a, horseshoe-shaped ridge round anus. 
„ 2. — Rostrum and palpi x about 200 ; a, first joint of palpus ; b, second 
ditto ; c, falx ; d, third joint of palpus. 
„ 3. — Larva. 
„ 4. — Foot highly magnified. 
* Subsequent to the reading of this paper Mr. Mclntire was good enough to 
show me a slide of unnamed Chejkt'is captured by him. It has been mounted 
some years, but I think it quite possible that it may have been this species, 
t ‘ Deutschland’s Crustaceeu,’ Heft xxiii. p. 22. 
VOL. I. 
Z 
