On Three new Parasitic Acari. 43 
irregular in form, 1 aboral, modified furrow spinelet, and 1 
suboral pointed spine; in interbrachium the first pair of 
adjacent adambulacral plates touch or join only at their 
proximal ends—are not fused the whole extent of their 
external or lateral faces, nor is there directly above them a 
prominent pair of first marginal plates as in Brisinga and 
Freyella, and allies. : 
Type-locality. — * Albatross’? station 2859, off British 
Columbia (55° 20’ N., 136° 20’ W.), 1569 fathoms, grey 
ooze, bottom temperature, 34°°9 Fahrenheit. 
LI1.—On Three new Parasitic Acari. 
By STANLEY Hirst. 
(Published by permission of the Trustees of the British Museum.) 
Family Listrophorida. 
The curious new mite briefly described below lives on the 
guinea-pig, being found on the hairs of the posterior part of 
the back. It is a minute species, and this is no doubt the 
reason why it has hitherto escaped notice. The mite clasps 
a hair of the host with its anterior legs, which are specially 
modified for this purpose. During copulation the male 
attaches himself to the generative nymph by the little suckers 
on the venter and also by the elongated legs of the fourth 
pair, the hook of the tarsus becoming fixed in the projecting 
posterior margin of the second epimeron. Whilst copulating 
the heads of both male and nymph point in the same direction, 
instead of in opposite directions as in the genus Schizocar pus. 
CHIRODISCOIDES, gen. nov. 
Anterior legs modified so as to form clasping-organs as in 
Chirodiscus, Trouess. & Nn., but a small pulvillus is present 
on the tarsi of these limbs. Fourth leg of male longer than 
the others, and its tarsus is bent at the end to form a hook, 
Body of the male not bifid at the end as is the case in Chiro- 
discus, but produced into a short unpaired process. ‘There 
are no long hairs on the body. 
Chirodiscoides cavic, sp. n. 
Body of ovigerous female narrow and elongated, being 
