9"^ 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXVIII. 



Fig. 179.— ScHizocARPi's mi.nuaudi, fe.m.\le, side view. 



Trouessiirt from Califoriiiu; ^1. dlgltafus Haller, on the Canadian war- 



l)U'r; and the European A. passeffnuK Linniwus recorded from several 



small birds. 



Family LISTROPHORID.E. 



The members of this family {Sarcopttdex <jl!rlcoJes of Megnin) are 

 closely related to the Ijird-mites, but live upon many of the smaller 

 mammals, includino- })ats. They are small, soft-bodied, and with short 



and stout legs, terminating in 

 a sucker and often a slender 

 claw. The l)ody usually tapers 

 a little 1)ehind, and the legs are 

 widely separate, one from the 

 other, sometimes each pair is 

 at an e([ual distance from the 

 adjoining ones. The dorsum has a few short hairs, with longer ones 

 at tip. The surface is usually transversely striate. The rostrum 

 or heak forms a distinct cone on the front of the body; the palpi are 

 simple, tiliform, and lie close to the underside of the beak; they are 

 three-jointed. The mandibles are com- 

 monly chelate, but \Qvy small. The gen- 

 ital apertures are situate between the third 

 and fourth coxa?, and the anus at the tip 

 of the body. The males, which are usu- 

 ally of a different shape than the females, 

 have a pair of copulatory suckers near the 

 tip of the venter. 



These mites feed on the hairs of small 

 mammals, and each genus has some special 

 apparatus wherewith to hold onto the hair. 

 In L'xfj'opJiorKS the under lip is expanded 

 on each side into a flexible plate w^hich 

 curls around the hair. They occur on 

 rabbits, squirrels, and mice. In Myocoptisx 

 the hind pairs of legs are enlarged, the 

 apical joints provided with a few large 

 spurs, and these joints can fold back on 

 the basal joints as a knife-])lade. By this 

 arrangement they cling to the hair of 

 mice. In TrirlKvcinx the hind tarsal joint is flattened, curved, and 

 provided with a spine, which enables the mite to grasp the hair of 

 mice. In Lahldocarpux^ which occurs on bats, the anterior legs are 

 very short and the last joint enlarged and concave below. By these 

 they clasp hairs. Tlu^ hind l(\gs arc^ normal. Sc/iizocarjjus has a 

 similar ai-rangement; it occurs on the beaver. In Chirodiscus the 

 anterior legs have the apical joints flattened and curled, but destitute 

 of claws and sucker. 



Fli:. ISO. — SlHIZl><Al!l'l'.S MIXUAl'M, 

 .MAI.K ANU FEMALE TOGETHER. 



