1 6 NORTH AMERICAN ANOPLURA 



third pair very large and stout with extremely broad, blunt claws and 

 usually with a short, pointed process on the anterior margin of the tibia. 

 Abdomen with well chitinized tergites and sternites, the fourth to sev- 

 enth tergites and third to sixth sternites of the female being transverse- 

 ly divided into three distinct plates, the remaining tergites and sternites 

 with either one or two plates, each plate with a transverse row of spines. 

 The males in general have a smaller number of plates than the females, 

 but the number is not constant thruout the genus. Anterior sclerite of 

 the third sternite, in both male and female, with four or six very large 

 and conspicuous spines. Pleural plates well developed, present on the 

 first to eighth segments, large, usually overlapping and with the posterior 

 margin variously toothed. 



The genus is composed chiefly of Murid-infesting species, of the 

 seven previously described species referable to it six being from Murids 

 and one from a Sciurid. We are adding three new species from Sciurids, 

 a new variety from Murids, and are recording one species, previously 

 described, which also occurs upon Murids. 



Hoplopleura acanthopus (Burm.) var. americanus n. var. 

 Plate IV, fig. 2 ; plate V, fig. 8 ; text fig. 3. 



Haematopinus acanthopus Osborn, Bui. 7, o. c, U. S. Dept. Agr., Div. Ent., p. 23, 



(1891). 



Numerous males and females from Microtus constrictus (Mendo- 

 cino City, Mendocino county, Calif.) ; Microtus calif ornicus (Covelo, 

 Calif.) ; Microtus sp. (South Yolla Bolly Mt., Tehama county, Calif.), 

 and three females and one male from "white lemming" (locality not 

 known, possibly Pt. Barrow, Alaska). Osborn records it as H. acan- 

 thopus, from Arvicola sp. (Ames, Iowa), but an examination of his speci- 

 mens has shown that they should be referred to this variety. 



The variety is very close to the species, apparently differing from it 

 only in the shape of the sternal plate, which has a more or less pro- 

 nounced, rounded projection on the lateral margin which is absent in H. 

 acanthopus. There is some variation but the character is usually plainly 

 apparent, and it seems to be sufficiently constant to warrant the naming 

 of a new variety. 



