32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I23 



caudomarginal bristles and three or four very small ones ; with a 

 subapical ventral sinus ; proximal to sinus with one or two long 

 bristles; membranous process (M.P.) present, narrow, and spiculated 

 on upper portion. Immovable process of clasper (fig. 58, P.) with 

 rather narrowly rounded apex, bearing several small bristles ; posterior 

 margin with characteristic long, stout median bristle. Digitoid or 

 movable finger of clasper (F.) broadest above middle, with posterior 

 margin strongly rounded, anterior margin fairly straight ; three long 

 and several shorter caudomarginal bristles on dorsal half ; two or 

 three slender bristles on anterior margin ; several small hairs on mesal 

 and lateral surfaces. Distal arm of ninth sternum (fig. 57) with an- 

 terior (dorsal) portion semimembranous from base to near apex; 

 apex truncate, bearing several very short bristles ; three or four long, 

 stout bristles near midpoint of markedly convex portion of posterior 

 (ventral) margin; with a fringe of smaller marginal and submarginal 

 proximal bristles. 



Aedeagits (fig. 114). — Distolateral lobe (DL.L.) shaped like an 

 old-fashioned bonnet; central thickening (C.TH.) represented by an 

 irregular sclerotized area. Apex of sclerotized inner tube (A.S.I.) 

 with its dorsal spur extending caudad, not dorsad ; associated with a 

 semimembranous, filamentous structure. Crochets (CR.) obtuse, with 

 base fairly well developed, quite broad and more than half as long as 

 spatulate or duckbill-shaped extension. 



Female. — Posterior margin of seventh sternum (fig. 56) with mar- 

 gin of upper lobe fairly straight ; very shallow sinus ; slightly convex 

 or straight below sinus to ventral margin. Anal stylet three times as 

 long as broad, with one long apical bristle and one somewhat shorter 

 subapical ventral bristle. Spermatheca (fig. 56, SP.) with head rather 

 evenly oval ; tail as long as head. 



Length. — Male, 2.0-2.2 mm. ; female, 2.45-2.9 mm. 



No types designated. Cotype hosts: Peromyscus canadianus (?), 

 Microtus drwnmondi and Evotomys ( = Clethrionomys) gapperi, 

 from Horse Creek, upper Columbia Valley, British Columbia ; Kick- 

 ing Horse Canyon, British Columbia ; Red Deer, Alberta. 



The range of this flea is the western United States and Canada, 

 east into the Rockies, and south to northern California. 



Records of Specimens Examined 



Canada. Alberta {Microtus sp.) ; British Columbia (Clethrionomys sp., 

 Microtus longicaudus (=M. viordax), Peromyscus sp.). 



United States. California: Fresno County (Microtus longicaudus sierrae) ; 

 Marin County (M. californiciis) ; Plumas County (Clethrionomys californicus. 



