30 



REPORT 108, U. S. DEPARTMENT OF AGRICULTURE. 



feed on matter secreted by the skin of the host. Several other species are found on 

 allied mammals, and one infests bats in Canada. Osbom has recorded the presence 

 of M. musculi Sclirank in this country. 



Picobia (figs. 33, 34) has an elongate body provided ^vith long bristles. They live 

 in the quills of the feathers of various birds, coming out only for breeding and mi- 



FiG. 32.—Fkobia hel- 

 Icri. (Original.) 



Fig. 3-i.~Picobia hcUcri: Tarsus and head. 

 (Original.) 



gration. One of these was recorded from Arizona by Hancock as Picobia villosa, 

 which Trouessart states is the same as P. bipectinatus Heller of Europe. Trouessart 

 also claims that this is not an adult mite, but that it is a stage (which he calls ''s\Tin- 

 gobial ") in the life of a Cheyletiella. Syringophilus (Picobia) is not a stage of Cheyletus 

 nomeri Trouess., as held by Trouessart, but a very distinct form; indeed Xorner had 

 described the male and egg of Syringophilus. The like- 

 ness between the two is a convergence due, as shown by 

 Oudemans, to their common habitat, the interior of the 

 quills of feathers, both being elongate and with short 

 legs. 



Family AXYSTID^. 



There are few species of mites in this family, but one 

 is very common and beneficial. Most of them are at 

 once separated from all other Trombidioidea in that tlie 

 coxae are close together and arranged in a radiate man- 

 ner. The body shows no complete division between 

 cephalothorax and abdomen, although in the t^-pical 

 genus the division is often indicated just bcliind the 

 third pair of legs. The body, which is usually short and 

 broad, is provided with many stout bristles. In front 

 on each side are one or two simple eyes. The mandi- 

 bles are quite large and prominent, and taper to a point which is tipped by a curved 

 claw. The palpi are prominent but slender; in Tarsotomus with a long "thumb/' 

 but in Anystis the last joint is torniinal. The legs are large and long, gradually 

 tapering and provided with many long hairs or bristles. They are six or seven 

 jointed, and terminate in two or three claws. In some species the tiu-sus is 

 divided into a number of small joints. On the venter (fig. 35; are genital and 



Fig. 35.— Venter of A nystis. (Au- 

 thor's illustration.) 



