the Genus Demodex, Owen. 



233 



Demodex ratti^ Halin. 



? . — 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. Capituluin narrow, being longer than 

 vvide. Cephalothorax also characteristically narrow and 

 much shorter than the abdomen ; the latter is wider, but 

 fairlj long and vermiform. The two spines on the dorsal 

 surface of the capitulam are well developed and fairly long ; 

 they are curved near the base and pointed at the end. 



Measurements. — Length of body (including capitulam) 

 237 yti j width of cephalothorax 27 /i, of abdomen 36 /i. 



Fiff. 1. 



Demodex rcitti, Halm. Dorsal view of capitulum. 



Material. — I have examined two adult female specimens 

 collected by Leslie Linzell from a wild rat [Rattus norvpgicus) . 

 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 tlie outer angle strongly salient laterally and 



Ann. & Mag. N. Hist. Ser. 8. Vol. xx. 16 



