208 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 106 



with a slender genuala, two rather small tibialae, a tapered spur 

 with a microspur just proximal to it, and a pretarsala. Leg III 

 with a genuala. Nonspecialized leg setae similar in form and ar- 

 rangement to those of E. setGsa but somewhat longer. Empodium 

 slender, longer than the claws. Fine punctae sometimes discerni- 

 ble on coxae; other leg segments apparently v/ithout punctae. 



Scutum : Somewhat similar in general form and outline to that 

 of E. blarina but larger and more extended at the posterolateral 

 corners. Apparently subject to distortion. Crescentic ridge 

 anterior to each pseudostignia ; usually obscured. No punctae 

 apparent. Pits usually present about midway between the postero- 

 lateral seta and the pseudostigma on each side. Setae similar to 

 those of E. sctosa. Sensillae widely clavate; heads truncate at 

 tips, closely covered with setules on the anterior surface, rather 

 sparsely covered on the posterior surface ; pedicels distinct. 



Anomaly : Perhaps induced by flattening an engorged specimen 

 on a slide, in one specimen the anterior and posterior margins 

 formed concentric curves, and a line drav>^n between the postero- 

 lateral setae fell anterior to the anteromedian seta. 



Standard data of a cotype of E. americana from Boise County, 

 Idaho : 



AW PW AP SB ASB PSB AL AM PL S 

 68 95 22 25 21 12 34 34 66 22 x 17 



Summary of standard data of five specimens, including the 

 cotype (AL's, AM's, and S's from four specimens) : 



AW 62-80, mean 70.4; PW 82-119, mean 99.4; AP 18-22, mean 20.4; 

 SB 25-44, mean 33.6; ASB 21-32, mean 25.4; PSB 8-18, mean 12.4; 

 AL 34-38, mean 35.3; AM 34-33, mean 36.3; PL 66-79, mean 72; 

 S 22-35, mean 29.5, Width of head of sensilla in four specimens, 

 15 to 17, mean 16. 



Eyes : Two pairs ; anterior pair lying just anterior to the pos- 

 terolateral setae. Diameters of anterior eyes of three specimens, 

 9 to 12, mean 10.3 ; of posterior eyes, 9 to 10, mean 9.7. 



Dorsal setae : Similar in form to those of E. dctosa. ileasure- 

 ments from four specimens: Length of humerals, 58 to 70; of 

 setae near the middle of the first posthumeral row, 44 to 54; of 

 posterior setae, 35 to 36. 



Dorsal formulae for five specimens: 



Idaho 



Boise County: 2 . . 12 . . 12 . . . . 11 . . 7 . . 2 

 Montana 



Ravalli County: 2 . . 10 . . 11 . . 2 . . 12 . . 8 . . 6 . . 2 



2 . . 11 . . 11 . . 1 . . 10 . . 7 . . 4 



2 .. 9 .. 11 .. 2 .. 10 .. 6 .. 6 



