Three new Parasitic Acari. 433 
The male deutonymph has a fairly long and slender poste- 
rior process or tail, which is furnished with minute denticles 
resembling those found on the venter. There is a double 
longitudinal series of scales running along the median line of 
the dorsal surface as in the generative nymph and larva, 
Besides this central series there are also numerous scattered 
scales on the dorsal surface. 
Protonymph.—A smaller nymph with a much shorter tail 
than the male deutonymph also occurs ; presumably it is the 
protonymphal stage. 
Larva.—The two anterior legs are modified to form clasping- 
organs, as in the other stages; the third pair of legs is 
slender and not modified. There is a very short but distinct 
curved hook-like tail or process at the posterior end of the 
body. 
Ova.—The eggs are attached singly by one end to a hair 
of the host ; they are narrow and elongated. 
Material_—Numerous specimens were found on the two 
guinea-pigs examined. 
Measurements.—Length of ovigerous female *46-"51 mm., 
of generant nymph *39 mm., of male 35 mm., of male deuto- 
nymph (incl. caudal process) ‘46 mm., of protonymph 
*31mm., of larva 243, of ovam 210. Width of ovigerous 
female 150 w, of generant nymph 160 yz, of ovum 54 yp. 
Family Demodecide. 
Genus DEMODEX, Owen. 
Tn his valuable papers * on the genus Demodex Friedrich 
Gmeiner gives a list of the fourteen described species and 
also the literature, recording a hundred papers on this subject. 
Two new forms from the hedgehog and dormouse are described 
below. 
Demodex muscardint, sp. n. 
? .—This Demodex is a short form and very like that of 
the honse-mouse, but has the capitulum wider as compared 
with its length. ‘The general shape of the body is also 
* “ Demodex folliculorum des Menschen und der Tiere,” Arch. Dermat. 
Syph., Wien, vol. xcii. 1908, pp. 25-96, 4 pls.; “ Die Acarus-raiide der 
Tiere,” Zs, Tiermed. Jena, vol. xiii. 1909, pp. 1-82, 81-108, 4 pls. 
Ann & Mag. N. Hist. Ser. 8, Vol. xx. 29 
