CASE 

 XIV. 



CHEESE MITES, ETC. 255 



Sub-family Tyx^oglyphid^ (Cheese Mites and their allies). 



The general characters of this section are a soft, smooth, fleshy, 

 whitish body, without any system of stride, or lines, disposed 

 around the body, but with a slight furrow, depression, or line of 

 separation, on the back between the second and third pair of legs 

 marking off the thorax from the abdomen — Mandibles chelate. 

 The tarsi in most species, although not in all, have only a single 

 claw, which is surrounded by a vesicle, or fine sucker, like a 

 sleeve. In a few species there is only a claw and no sucker. 



The group consists of the following genera— Rhizoglyphus, 

 Tyroglyphus, Glyciphagus, and Cheyletus, which may be distin- 

 guished by the following characters : — 



Rhizoglyphus, Tyroglyphus, and Glyciphagus have the typical 

 characters above mentioned, but are distinguished from each 

 other by the two former having the hairs on the back smooth, 

 while in Glyciphagus they are hairy, plumose, or feathered, and 

 in it there is also a posterior appendage in the females, like a knob 

 at the tail, or an os coccygis. Rhizoglyphus again is distinguished 

 from Tyroglyphus by having tarsi with claws, and without suckers, 

 while Tyroglyphus has both a claw and sucker. 



Cheyletus is distinguished by its enormous mandibles, by a 

 peculiar tracheal system, and by having two claws, and other 

 appendages to the tarsi. 



Genus Tyroglyphus {Lat.). 



Sub-genus Rhizoglyphus. 



Tarsi with claws and without suckers. Feeds on vegetable 

 substances. 



Claparede (loc. cit.) proposed in 1868 a genus under this 

 name for a species of Tyroglyphus, which we shall presently 



