the Genus Demodex, Owen. 233 
Demodex ratti, Hahn. 
2 .—This species is long and slender, being about seven 
and a half to eight and a half times as long as the width of 
the cephalothorax. Capitulum narrow, being longer than 
wide. Cephalothorax also characteristically narrow and 
much shorter than the abdomen; the latter is wider, but 
fairly long and vermiform. The two spines on the dorsal 
surface of the capitulum are well developed and fairly long ; 
they are curved near the base and pointed at the end. 
Measurements.—Length of body (including capitulum) 
237 «; width of cephalothorax 27 jz, of abdomen 36 [Le 
Demodex ratti, Hahn. Dorsal view of capitulum. 
Material—I have examined two adult female specimens 
collected by Leslie Linzell froma wild rat (Rattus norvegicus) . 
Mr. Linzell informs me that the parasites were very abundant 
in the skin of this rat. 
Demodex musculi, Oudms. 
The adults of this species are rather short. Cephalothorax 
+capitulum a little shorter than abdominal part of body. 
Capitulum of moderate width, being widest at the base, where 
it is about equal to the length. Distal end of capitulum 
(palp) with the outer angle strongly salient laterally and 
Ann. & Mag. N. Hist. Ser. 8. Vol. xx. 16 
