DESCRIPTIONS OF GENERA AND SPECIES. 247 



personally cannot see that A. setosus, Koch, can be 

 either G. spinipes or G. domesticus ; it seems to me 

 to be different from both. 



Lackerbauer's drawing of this species, which illus- 

 trates Fumouze and Robin's paper, is, in my opinion, 

 one of the finest drawings of an Acarus ever pub- 

 lished. 



Female. Male. 



Length . . . . '45 to '80 mm. '40 to '50 mm. 



Typical length of English speci- 

 mens about . . . . '70 mm, *45 mm. 



Typical breadth of English speci- 

 mens about .... "45 ,, '24 



Typical length of legs, first and 



second pairs, about . . . '36 "30 



Typical length of legs, third pair, 



about . . . . -45 '34 



Typical length of legs, fourth pair, 



about . . . . '51 ,, *36 



As to the means of distinguishing this species from 

 G. domesticus, see the description of the latter species. 



This is an abundant and widely distributed creature. 



Colour pearly white or pale grey. Rostrum, tarsi, 

 and epimera reddish. 



Texture nearly smooth, but not polished ; almost the 

 texture of chamois leather, but slightly granular. 



Shape, Conical anteriorly, with strong indentations 

 for the reception of the first and second pairs of legs. 

 These indentations are bordered by a narrow chitinous 

 band. Body sharply constricted near the insertion of 

 the third pair of legs ; the portion of the body behind this 

 constriction is considerably narrower than the part imme- 

 diately before it ; posterior margin rounded. 



Female. Rostrum blunt, palpi showing plainly at 

 the side of the mandibles. Mandibles (PL VII, fig. 8) 

 with the fixed arm of the chela quadridentate, the 

 moveable arm tridentate, but with the proximal tooth 

 slightly bifid. Berlese * makes the dentition more 

 elaborate than I do. I have not, however, been able 

 to see the mandible quite as he draws it in any speci- 



* Loc. cit., fasc. xiv, No. 2, tig. 6. 



