666 ACAIIINA. 



states that during summer this mite is viviparous. T. farhice 

 DeGeer, as its name indicates, is found in flour. Other species 

 have been known to occur in ulcers. 



We figure the hirva of the European TypModromus pyri 

 (Plate 13, fig. 4) the adult of which, according to A. Scheuten, 

 is allied to Tyrogljphus, and lives under the epidermis of the 

 leaves of the pear. There are but two pairs of legs present, 

 and the body is long, cylindrical and worm-like. Fig. 5, plate 

 13 , represents the four-legged larva of another species of 

 Typlilodromus. 



The Itch mite belongs to the genus Sarcoptes^ in which the 

 body is rounded ovate, with needle-like mandibles, and with 

 short three-jointed legs. The female differs from the male in 

 having the two hinder pairs of legs only partially developed, 

 and ending in a long bristle. S. scabiei Linn. (Plate 13, fig. 

 7, female) was first recognized by an Arabian author of the 

 twelfth century as the cause of the disease which results from 

 its attacks. It buries itself in the skin on the more protected 

 parts of the body, forming minute galleries, by which its pres- 

 ence is detected, and by its punctures maintains a constant 

 irritation. 



Other species are known to infest the cat, dog and swine. 

 They are best dcstro3'ed by the faithful use of sulphur oint- 

 ment. Various species of an allied genus, Dermatodectes, live 

 in galleries on different species of domestic animals ; thus D. 

 equi lives in the skin of the horse, D. bovis in cattle, and D. 

 oris in sheep. Various 8arcoptids occur on birds ; among 

 them are species of DermaleicJms. On March 6th, Mv. C. 

 Cooke called my attention to certain female mites (Plate 13 

 fig. 1) which were situated on the narrow groove between the 

 main stem of the barb and the outer edge of the barbules of 

 the feathers of the Downy Woodpecker, and subsequently Ave 

 found the other forms indicated in Plate 13, figs. 2 and 3, in 

 the down under the feathers. These long worm-like mites are 

 probably the females of the singular male Sarcoptes-like mite, 

 represented by Figs. 2 and 3 of the plate, as they were found 

 on the same specimen of woodpecker at about the same date. 



The female (though there is probably a still earlier hexai)o- 

 dous stage) of this Sarcoptid, which we may call Dermcdeichus 



