VOL. lol 



238 PROCEEDINGS OF THE NATIONAL MUSEUM 



and structure of epistome as in female; legs as in female, with no 

 enlarged setae or other evidences of sexual dimorphism. Nymph: 

 Setation, mouth parts, and legs as in female; differs from nymphs 

 of other species in that genitoventral setae are on ventral shield 

 _ Oudemans (1913) figures the adult female of this species as possess- 

 ing only the three usual setae on the anal shield. However, Michael 

 (1892) figures about 13 accessory setae, and Hirst (1916) reports 14 

 anal setae from one specimen and 9 on another. Vitzthum (1931) 

 comments that 6 to 11 accessory setae had been reported on specimens 

 of this mite taken in Great Britain. 



Although both Oudemans and Vitzthum describe specimens exam- 

 ined by them as possessing only smooth setae, many dorsal and ventral 

 body setae are barbed in specimens that I examined. 



Sise.—Four females in the U. S. National Museum collection meas- 

 ure 1,372/., 1,400/., 1,442/x, and 1,512/x in length. It was impossible 

 to obtain accurate measurements of width. The only nymphal speci- 

 men available was 994/. in length. Michael gave the length of the 

 female of this species as about 1,400/. and that of the male as 1,160/.; 

 width of female 770/.; of male 650/.. Vitzthum gives the length of 

 the female as 1,530/.; of the male as 1,270/.. 



Distribution and Ar?s^5.— Michael's original description was based 

 upon specimens taken from nests of the mole Talfa europea in Great 

 Britain. Oudemans reported it from rodent nests in Holland ; Hirst 

 from field mice and their nests in Great Britain; and Vitzthum 

 describes this species as a parasite of mice and moles of various 

 species in western Europe. I have examined specimens as follows : 

 from nest of Apodemus ilavicolUs, Eatece, Slovenia, August 14, 1931 ; 

 Talpa alpina, Eatece, Slovenia, July 12, 1931; Apodemus sylvaticus 

 North Bull, Dublin, Eire, October 6, 1946 (E. W. Jameson collection) ; 

 "mouse nest," Hell Coppice, near Oaklev, Bucks, England, August 

 17, 1941 (E. W. Jameson collection). 



Status of H. arvicolarum {Berlese).—Berlese (1920) described 

 arvicolarum as a variety of horridus on the basis of specimens taken 

 from nests of Arvicola arvalis at Ferrara, Italy, and Asuni, Sardinia. 

 These differed from horridus, as described by Michael, in the follow- 

 ing respects: Somewhat smaller; legs relatively shorter and thicker; 

 terminal body setae no longer than other marginal setae; chelae of 

 female stronger than in horridus : leg II of male with enlarged ventral 

 setae. Length of female was given as 1,300/.; that of male as 1,060/.. 

 No figures were given. None of Berlese's material was available for 

 study. 



Turk (1945) found the characteristics described by Berlese in a 

 series of specimens taken from the nest of Apodemus sylvaticus sylva- 



