336 



THE ARACHNOIDS 



produced is at times called autumnal erythema. There is a Trombidium in Mexico 

 which has a predilection for the skin of the eyelids, prepuce, and navel. The Kedani 

 mite, an orange-red larval mite about 250 by 125 microns is believed by the Japanese 

 authorities to bring about infection with Japanese river fever or Tsutsugamushi, 

 as the result of transmitting either a bacterium or protozoon by its bite. The 

 disease somewhat resembles typhus, although an eschar at the site of the bite and 

 lymphatic involvement is present. 



Gamasidae 



Of the Gamasidae, which generally have a hard leathery body and styliform 

 piercing chelicerae, delicate five jointed palps and styliform hypostome, only the 

 Dermanyssus gallina is of interest. This mite infests chicken-houses and sucks the 



FIG. 79. Arachnoidea exclusive of ticks. (ia) Sarcoptes scabiei, female; .(ib) S.- 

 scabiei, male; (2) Demodex foUiculorum; (3) Trombidium akamushi, hexapod larva 

 (Kedani mite); (4) Trombidium holosericeum larva (Leptus); (5) Dermanyssus 

 gallina; (6) Tyroglyphus longior; (7 a) Pediculoides ventricosus, male; (76) P. ventri- 

 cosus, young male; (7^) P. ventricosus impregnated female; (8) Porocephalus armll- 

 latus; (90) Linguatula serrata, female; (96) L. serrata, larva. 



blood of the inmates. They will also attack man. Poultrymen may be troubled 

 with a sort of eczema on the backs of the hands and forearms, similar to scabies, 

 resulting from bites by these mites. They measure 350 X 650^1. They have no 

 eyes. 



Tyroglyphidae 



Mites of this family live on cheese, flour, dried fruits, etc. They are small, 

 without eyes, and have a smooth skin and a cone-like appearance of the mouth 



