NO. 4 FLEA GENUS PEROMYSCOPSYLLA — JOHNSON AND TRAUB 37 



Thorax.— As, in hesperomys, except no erect dorsal bristles on 

 mesonotum. 



Abdomen.— hnitnor row of bristles on terga quite long, even on 

 sixth and seventh terga in both male and female. Male with three 

 antepygidial bristles, female with five. 



Male.— Ttrgnm 8 posterior to spiracle with bristles arranged 2-3, 

 those of posterior row the longer. Eighth sternum (fig. 70 in shape 

 much as h. hamifer, but with dorsal extension or fold from base to 

 near apex dorsally ; with two very long lateral subapical bristles and 

 two small light bristles at dorsal angle of apex; one or two stout 

 bristles basally. Characteristic bristle on posterior margin of im- 

 movable process of clasper (fig. 65, P.) stout and longer than width 

 of movable finger. Movable finger or digitoid of clasper (F.) broadest 

 at apex with straight anterior margin, convex posterior margin ; dorsal 

 margin slightly convex; three large bristles posterodorsally. Distal 

 arm of ninth sternum (fig. 72) with semimembranous dorsal (ante- 

 rior) subapical margin ; posterior (ventral) margin strongly rounded, 

 bearing several medium-sized bristles and basally some small bristles ; 

 laterally with scattered row of thin bristles ; apex with several small 

 thin bristles. 



Aedeagus (fig. 113).— Aedeagal end chamber definitely broader than 

 long, due to the marked convexity of lateral lobes {L.L.). Distolateral 

 lobe (DL.L.) relatively small in proportion to width of end chamber. 

 With a well-developed central thickening (C.TH.). Sclerotized inner 

 tube (S.I.T.) lacking a ventral sclerotization. Armature of inner tube 

 (A.I.T.) consisting of a small dorsomedian spur. Apex of sclerotized 

 inner tube (A.S.I.) not expanded. Crochets (CR.) with usual sagit- 

 tate element, short and blunt, its base relatively long, in addition, with 

 weakly sclerotized outlines (CR.O.) indicating that true crochet is 

 subovate and about twice as long as broad. The aedeagus is apparently 

 similar in all subspecies of silvatica. 



Fma/^.— Spermatheca (fig. 67, SP.) as in hesperomys; posterior 

 margin of seventh sternum (fig. 67) with a shallow but distinct ventral 

 sinus. Anal stylet 3^ times as long as wide, with one long apical 

 bristle and two shorter subapical ones. 



Type. From Frijsenborg, Denmark, from mouse nest in tree 



stump in woods. 



The range of s. silvatica is apparently most of Europe and Asia, 

 except the British Isles and European Alps, where it is replaced by 

 s. spectabilis and s. fallax respectively. 



