NO. 4 



FLEA GENUS PEROMYSCOPSYLLA — JOHNSON AND TRAUB 6l 



men very granular). Immovable process of clasper (F. and fig. 96) 

 truncate, dorsal and ventral margins subparallel ; lacking characteristic 

 bristle ; at insertion of movable finger on posterior margin about five 

 small apical and subapical bristles. Digitoid or movable finger of 

 clasper (F.) i^ times as long as broad ; convex posterior margin with 

 three long bristles above and two below middle. Distal arm of ninth 

 sternum (D.A.p and fig. 98) poorly sclerotized ; with apical portion 

 narrowed, subtruncate; posterior (ventral) portion with a fringe of 

 many rather long bristles. 



Figs 122-123.— Peromyscopsylla ostsibirica: 122, Clasper, eighth and ninth 

 sterna,^ (from Skalon, 1950) ; 123, spermatheca and seventh sternum, V (from 

 Skalon, 1950). For explanation of symbols see pages 67-feb. 



Aedeagus (figs. 94 and 121).— Lateral lobes (L.L.) very broad, so 

 that end chamber is more than twice as broad as long. Median dorsal 

 lobe {M.D.L.) well sclerotized, becoming bifid above crescent sclerite 

 {C.S.). Distolateral lobes {DL.L) represented only as a small indis- 

 tinct sclerite lying above sclerotized inner tube (S.I.T.). Apex of 

 sclerotized inner tube {AS.I.) conspicuously turned dorsad. Band of 

 inner tube {B.I.T.) relatively well developed. Armature of inner tube 

 not developed. Crochets (CR.) very conspicuous, about 2^ times as 

 long as broad ; subovate or slipper-shaped ; with a median acuminate 

 lateral thickening which apparently is all that remains of the crochet 

 in many other species of Peromyscopsylla. 



The aedeagus of P. tikhomirovae is apparently primitive in several 

 respects : the large crochet which is fairly well sclerotized ; the bifid 

 median dorsal lobes ; the small inconspicuous distolateral lobes ; the 

 absence of the fulcrum ; and the lack of armature on the inner tube. 



Female (fig. 95).— Sternum seven (/S.) with slightly undulate 

 posterior margin. Anal stylet {AS. and fig. 93) I3 times as long as 



