170 



ARACHNOIDEA. 



CASE inhabitants, and they sosLietimes migrate from the birds to the per- 

 sons of those who have charge of them, and occasion them much 

 annoyance. Alt (a German observer) saw these mites, or a mite 

 which he supposed to be of the* same species, upon the neck and 



Dermanyssus avium, full fed (upper side). 



About the size of the cheese mite. 



Ditto, empty (under side). 



arms of a cachectic old woman. According to him they were 

 white, of the size of a grain of sand, extremely agile, and slipped 

 out of little excavations (occupying the space of ij square 

 line), ran over the skin, and back again into their holes. 



Simon narrates a case in which the mite nestled up©n the skin 

 of a woman, who was otherwise healthy. She was constantly 

 infested with little louse-like animals, notwithstanding great clean- 

 liness and many attempts at extirpation of the mites, which were 

 recognised by Erichson as the Dermanyssus avium. It was 

 found at last that the woman went several times daily into the 

 cellar, over v/hich the hen-roost lay. As often as this was the 

 case, the fowls flew up into their roosting-place, and by this means 

 the woman was sprinkled with mites. The removal of the hen- 

 roost cured her of her supposed phthiriasis. (Kuchenmeister, 

 Manual Parasites, vol. 2, p. 64.) 



It also infests dove-cotes ; although no doubt it is sometimes' 



