THE GENUS DEMODEX. 33 



first and second pairs of legs ; the operculum and other genital structures 

 present some resemblance to those of D. bovis. 

 Measurements : — 



Male. 



Total length of body (incl. capit.) 127 /u 



Length of cephalothorax + capitulum 65 ft 



„ abdomen 62 /u, 



Greatest width of cephalothorax 39 /a 



„ „ abdomen - . . 36-37 /* 



„ ,, capitulum (at base) 28 /x 



Length of capitulum 19 /* 



Host ; Stoat {Mustela ermined). Two males from a Stoat trapped in the vicinity 

 of Exeter, Oct. 1918. 



10. DEMODEX ARVICOL^, Zschokke, 1888. 

 D. arvicolci', Zschokke, Schweizer Arch. f. Tierheilk. 1888, vol. xxx. p. 69. 



(Plate IX. fig. 37.) 



$ . This is the typical form and apparently sometimes reaches a 

 slightly greater length than the variety miisculi. (Zschokke's specimens 

 evidently were much larger.) Body from less than 4^ up to almost six 

 times as long as the Avidth of the cephalothorax. Abdomen longer 

 than cephalothorax+capitulum. Capitulum about as wide as long. 

 Penultimate segment of palp strongly salient and pointed laterally. 

 Dorsal spines on capitulum well developed and pointed, as in the 

 var. musculi. 



Author's measurements: — 



Host : Field Vole {Microtus [Arvicola] agrestis). Two adult female specimens of the 

 mite from an example of this mammal caught near Eton. 



D 



