MITES OF SUBFAMILY HAEMOGAMASINAE — KEEGAN 257 



cessory setae immediately posterior to usual genitoventral setae; 

 epistome as in adult female ; chelicerae as in female. 



Measurements indicated that male, female, and nymph of this form 

 are larger than those of Uponyssoides. 



Distribution and hosts. — All specimens of occidentalis have been 

 taken from northwestern United States and southwestern Canada. 

 Records: Mustela saturata., Linton, Oreg., May 22, 1933. Scapanus 

 townsendU, Olympia, Wash., June 25, 1934; Wilsonville, Oreg., May 

 10, 1938 ; Lake County, Oreg., November 7, 1934 ; Clackamas County, 

 Oreg., May 30, 1932 ; Castle Rock, Wash., March 30, 1927. Scapanus 

 orarius schefferi^ Vancouver, British Columbia, March 29, 1938. 

 Scapanus orarius^ Olympia, Wash., August 16, 1926. Neilrotrichus 

 sp., Netarts, Oreg., March 24, 1930 ; Portland, Oreg., June 23, 1933. 

 Nest of Microtus toivnsendii, Portland, Oreg., June 23, 1933. Microtus 

 townsendii, Portland, Oreg., Dec. 6, 1931. Sorex trowhridgii., Cala- 

 veras Dam, Alameda County, Calif., April 15, 1945. Thomomys 

 fuseus, Colfax, Wash., April 14, 1927. Blarina hrevicauda talpoides^ 

 Morgan, Utah, August 31 and September 8, 1931. 



Type.— A. female (U. S. N. M. No. 1886) taken from nest of Microtus 

 townsendii at Portland, Oreg., on December 24, 1931, by S. G. Jewett, 

 Jr. 



Paratypes. — A male on slide with type, two females, one male, two 

 nymphs, from /Scapanus tow7isendii, Wilsonville, Oreg., May 10, 1938, 

 H. H. Stage, Bish. No. 17174 ; three females, one nymph, from Scapa- 

 nus townsendii; Lake County, Oreg., November 7, 1934, H. H. Stage, 

 Bish. No. 17075 ; two nymphs, from Scapanus toiansendii; Castle Rock, 

 Wash., March 30, 1927, Leo K. Couch; one male, from Thomomys 

 fuscus, Colfax, Wash., April 14, 1927, Leo K. Couch. 



Discussion. — The three paratype females and single nymph from 

 Scapanus townsendii^ Lake County, Oreg., exhibit some characteris- 

 tics that seem to be intermediate between Uponyssoides and occiden- 

 talis. Distinctive features of these specimens are : Dorsal shield rela- 

 tively narrower than in other specimens of occidentalis; setae on 

 shield of nearly uniform size. Sternal shield intermediate in outline 

 between Uponyssoides and occidentalis in that its posterior margin is 

 invaginated to a level slightly anterior to posterior pair of sternal 

 setae ; distance between middle pair of setae and anterior and posterior 

 pairs about equal. Genitoventral shield relatively narrower than in 

 either Uponyssoides or occidentalis and with fewer accessory setae: 

 10, 13, and 13 on the three females on the slide. Anal shield may be 

 relatively shorter than in Uponyssoides or occidentalis; posterior pair 

 of accessory setae only slightly anterior to anus. Ventral body setae 

 slightly smaller than those of dorsal shield. Shape of posterior end 

 of peritreme distinctive. Epistome with five to eight lateral fimbriae 

 on each side. 



