454 ENTOMOLOGICAL NEWS [Dec., '13 



abdomen on its ventral surface, the anterior end of the mite 

 being directed toward the head of the fly. The reason for the 

 mite always taking this position is not quite clear at present. 

 I can see two advantages in it, however; first, the mite is in 

 a place protected from the attacks of its host; second, this po- 

 sition does not throw the fly out of balance when flying. In 

 all cases thus far only the females of this parasitic mite have 

 been found. The description of the species follows. 



DESCRIPTION OF SPECIES. 



Macrocheles muscae n. sp. 



General appearance stout, robust; integument well chitinized, hence 

 color a dark yellowish brown. Body clothed very sparsely with small, 

 simple, curved bristles. 



Mouth-parts well developed. Palpi about one-half as long as first 

 pair of legs ; first segment longest, concave on its inner margin, and 

 about four-fifths as long as femur of leg I ; second segment slightly 

 shorter than the first ; third subequal to the second ; fourth slightly 

 over one-half as long as the third, bearing many setae or hairs and a 

 long prominent bristle slightly longer than the segment itself on its 

 outer margin ; distal segment very short, about one-third as long as 

 segment four, and immovably joined to this segment; it has many 

 bristles, a prominent spine at its base on the inside, and a long, slightly 

 curved, tactile spine at its apex. Chelicerae retractile, when extended 

 slightly surpassing the palpi ; geniculate at about their middle, and 

 strongly chelate at the apex; chelae stout, well chitinized, each with a 

 prominent tooth on its inner margin ; fixed chela with a small spine on 

 its upper margin about one-third the distance from its base to apex ; 

 at the base of the fixed chela on its lower side is situated a long pectin- 

 ate seta, about equal to the chelae themselves in length and with barbs 

 on one side only. Hypostome prominent ; about two and one-half 

 times as long as broad, with three prominent bristles, and ending in 

 two large cusps, between which is the tongue or lingula ; lingula as 

 long as the cusps of the hypostome, with some hairs along its sides, 

 divided at its median line into halves each of which ends in a curved 

 setaceous tip. 



Cephalothorax not demarcated from abdomen; bearing a pair of 

 small anteriorly directed setae on its anterior margin near the median 

 line. Shoulder bristles but little larger than the other bristles of the 

 body. Sternum extending to between the third pair of coxae ; pos- 

 terior margin concave. The sternum bears three pairs of subequal, 

 backwardly directed, simple, almost straight setae. 



Abdomen broad, evenly rounded behind. Peritreme extending from 



