6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I23 



ventral (posterior) margin of distal arm of ninth sternum (fig. 

 yz) as long as distance between most-apical long bristle and apex 

 of ninth sternum (Great Britain) . .silvatica spcctabilis (Rothschild), p. 39 

 Movable finger not expanded dorsocaudally ; with patch of small 

 proximal bristles (figs. 65, 68, F.) ; long bristles on ventral 

 (posterior) margin of distal arm of ninth sternum (figs. 70, 72) 

 definitely shorter than distance between most-apical long bristle 

 and apex of ninth sternum 13 



13. Movable finger (fig. 65, F.) more than two times as long as broad 



at widest point; apical half of eighth sternum (fig. 71) broadest 



apically (Europe and Asia) silvatica silvatica (Aleinert), p. 36 



Movable finger (fig. 68, F.) less than two times as long as broad at 

 widest point; apical half of eighth sternum (fig. 69) broadest sub- 

 apically (European Alps) silvatica fallax (Rothschild), p. 41 



14. Genal lobe less than one-half length of lower genal spine (fig. 43, 



G.L.) ; no erect bristles dorsally on mesonotum (fig. 23) 15 



Genal lobe more than one-half length of lower genal spine (fig. i, 



G.L.) ; erect bristles dorsally on mesonotum (figs. 4, 21, 22) 17 



15. Frontal angle of head sharp (fig. 43) ; movable finger (fig. 47, F.) 



almost as broad as long ; apically, eighth sternum bearing three or 

 four long and three or four shorter marginal and submarginal 



bristles (fig. 45) draco Hopkins, p. 26 



Frontal angle of head more rounded (fig. i) ; movable finger (figs. 

 41, 49, F.) almost two times as long as broad; apically, eighth 

 sternum bearing no more than three bristles (figs. 39, 52) 16 



16. Crochet extremely short, base only well-sclerotized portion (fig. 



107, CR.) ; apex of eighth sternum (fig. 52) truncate, bearing 

 three very long apical bristles ; movable finger strongly produced 



dorsocaudally (fig. 49, F.) scotti I. Fox, p. 27 



Crochet (fig. no, CR.) longer than sclerotized inner tube (S.I.T.) ; 

 apex of eighth sternum (fig. 39) narrowly rounded, bearing two 

 medium-sized and one small bristle; movable finger (fig. 41, F.) 

 not strongly produced dorsocaudally ebrighti (C. Fox), p. 24 



17. Lower margin of immovable process of clasper (fig. 10, P.) less 



than one-half length of upper margin; movable finger (F.) more 

 than two times as long as broad (eastern United States and 



Canada) hcspcromys hesperomys (Baker), p. 8 



Lower margin of immovable process of clasper (figs. 17, 19, 29, P.) 

 more than one-half length of upper margin; movable finger (F.) 

 not more than two times as long as broad 18 



18. Erect dorsal bristles on mesonotum very heavy and dense, especially 



anteriorly (fig. 21) ; anterior margin of head almost vertical (fig. 

 14) (northern Rocky Mountain area) 



hesperomys ravalliensis (Dunn), p. 14 

 Erect dorsal bristles fine and not dense (fig. 22) ; anterior margin 



of head definitely oblique (fig. 13) I9 



19. Movable finger broadest at middle; about two times as long as 



broad (fig. 17, F.) (Pacific Northwest: Canada, United States) 



hesperomys pacifica Holland, p. 19 



