OF WASHINGTON. 



213 



are, however, chelate, and of the true Gamasid type. The palpi 

 are free, and the other characters do not depart from those of 

 Dermanyssus sufficiently to merit notice. The shape of the dor 

 sal plate and elongate body are rather anomalous, but not char 

 acters of importance. 1 shall therefore consider Halarachne a 

 genus of Dermanyssidae, not greatly.differing from the other mem 

 bers of that family ; but showing certain adaptive characters that 

 fit it for its peculiar surroundings. 



Our species appears to be different from the European form ; 

 and I describe it as follows : 



FIG 15. Halarachne ajnericana. : a, sternum of male ; b, stig 

 mata and coxae ; c, mandible; all enlarged. (Original.) 



Halarachne americana, n. sp. 



White, hard parts pale yellowish; smooth, body narrowed in front, 

 contracted behind the fourth pair of legs, broadly rounded at tip; a dorsal 

 shield on basal half, narrow in front, broadest before the middle, then 

 tapering behind, but broadly rounded at tip, showing an irregular cross 

 and some geminate spots; a small round hard spot near tip of body at the 

 anus; legs short and stout, second pair stoutest, with a few short bristles, 

 and two claws at tip, the terminal joint longer than the others which are 

 subequal ; stigmata just above the fourth coxae; sternal plate truncate in 

 front, sides nearly parallel at first, then concavely tapering to the bluntly- 

 pointed apex. 



