TYROGLYPHUS 375 



sexual orifice. The mouth-parts form a cone with chelate chelicerae, and 

 three-jointed pedipalpi ; the legs are usually short, have five segments with 

 a terminal claw and suckers, or either one or other of these organs. The 

 numerous species and genera live free and from choice in slowly decom- 

 posing vegetable and animal matter (cheese, cereals, flour, sugar, pre- 

 serves, dried anatomical preparations, bacon, dried fruits and fungi), also 

 in the corners of dwellings, &c. ; they incidentally get into or on to man, 

 or are found in chamber utensils and in spittoons ; actual parasites are 

 rarely found amongst them. 1 



[The chief genera are Tyroglyphus, Glyciphagus, Rhizoglyphus and Chey- 

 letus. The first three have typical characters referred to, but are dis- 

 tinguished from each other by the two former having the hairs on the 

 dorsum smooth, whilst in Glyciphagus they are hairy, plumose, or feathered. 

 Rhizoglyphus can be told from Tyroglyphus by having claws on the tarsi 

 without any suckers ; Tyroglyphus has both claws and suckers. Cheyletus 

 has enormous mandibles and a peculiar tracheal system ; two ungues and 

 appendages to the tarsi. F. V. T.] 



Tyroglyphus farince (De Geer). 



The male measures 0-33 mm. in length by 0*16 mm. in breadth ; 

 the female o'6 mm. in length by 0*3 in breadth. These mites 

 possess five pairs of suctorial organs of a light colour ; the legs are 

 reddish. Moniez observed them in Lille on the skin of labourers 

 who had been unloading Russian corn. 2 A few of the species 

 generally mentioned under the designation of Tyroglyphus siro are 

 probably the common Flour-mite, which also occurs on dry cheese. 



Tyroglyphus siro (L.). 



Male 0-5 mm. in length by 0*25 mm. in breadth ; 'female 0-53 

 mm. in length by 0-28 mm. in breadth ; the males have two 

 suckers on the tarsi of the fourth pair of legs. Penis straight. 

 Colour whitish or reddish. 



Tyroglyphus longior, Gervais, 1844. 



White or yellowish, with two black spots on the abdomen. 

 Male 0-55 rnm. in length, 0*28 mm. in breadth ; penis bent. 

 Female o 61 mm. in length and 0-28 mm. in breadth. 



Tyroglyphus siro and T. longior live on dry cheese, in flour, on 



1 Moniez, R., " Sur les Tyrogl. qui livent aux defiens d. mat. alim. ou d. prod, phartn." 

 (Rev. biol. du Nord de la France, 1899, vi.).- 



2 Moniez, R., " Parasit. accid. sur Vhomme du Tyr. far." (C. R. Ac. sc., 1889, Paris/ 

 cviii., p. 1026). 



