12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I23 



distinct sinus between upper lobe and lower lobe ; latter acuminate, 

 very small, bearing a row of two or three ventral subapical bristles ; 

 membranous process (M.P.) associated with eighth sternum, visible 

 only as vertical band on mesal surface. Immovable process of clasper 

 (P. and fig. lo) with narrowly rounded apex; dorsal margin at least 

 two times as long as ventral, long, oblique ; ventral margin subhori- 

 zontal (average measurements : ventral, 8i microns ; dorsal, 205 

 microns) ; bearing apically two or three very small bristles and on 

 straight posterior margin a characteristic small bristle about one-half 

 as long as greatest width of digitoid (average length 48 microns) and 

 inserted well below middle of margin. Digitoid or movable finger of 

 clasper (F. and fig. 10) with posterior margin evenly and broadly 

 convex from base to apex ; almost always more than two times as long 

 as broad (average width, 86 microns; length, 196 microns) ; area of 

 greatest width about at middle ; with three long bristles and two or 

 three smaller ones on posterior margin ; with several small mesal and 

 lateral bristles and three or four long slender bristles on rather straight 

 anterior margin. Distal arm of ninth sternum {D.A.g, and fig. 6) 

 not as long as proximal arm (P.A.p) ; with apex subtruncate but 

 upper angle acuminate and extending distad of arcuate ventral mar- 

 gin; entire posterior (ventral) margin clothed with short, thin bristles 

 and with about four long ventral bristles ; anterior (dorsal) margin 

 semimembranous most of its length. 



Aedeagus (figs. 7, 104-106). — Aedeagal apodeme (AE.A.) about 

 five times as long as broad. Distolateral lobe (DL.L.) about twice as 

 long as broad ; basal half weakly sclerotized and indistinct ; subovate, 

 but somewhat narrow near midpoint. Central thickening (C.TH.) 

 fairly well developed. Lateral lobes unspecialized, broad, usually 

 minutely spiculose subapically. Median dorsal lobe (M.D.L.) weakly 

 sclerotized. Sclerotized inner tube (S.I.T.) four times as long as 

 broad ; its armature (A.I.T.) represented as a dorsal basal thickening 

 which terminates in a short spur below midpoint ; lacking a lateral or 

 ventral sclerotization or keel. Apex of sclerotized inner tube (A.S.I.) 

 dorsally produced into a vertical arm. Band of inner tube (B.LT.) 

 reduced but distinct, appearing as a short apical extension from apex 

 of inner tube. With a conspicuous fulcrum (FM.) extending from 

 ventral portion of S.I.T. to base of DL.L. in vicinity of central thicken- 

 ing (C.TH.). Crochets (CR.) represented only by very long, narrow, 

 acuminate, daggerlike structures, longer than S.I.T. Accessory lateral 

 lobe (A.L.L.) acuminate. 



There are apparently no significant differences in the aedeagi of 

 the subspecies of hesperomys. 



