F'iG. 25. — Hexapoda-Ephcmeroptera : external male genitalia and associated 

 structures. 



A, Ephemera siiinilaiis, posterior part of abdomen, ventral view. B, same, 

 styli and stylus-bearing plate removed, exposing bases of penes and supporting 

 arms. C. Biasturus iicbnlosus. penes, ventral view. D, Habrophlebiodcs bef- 

 toni, penis, ventral view. E, Trichoryfhrodes jallax, penis, ventral view. F, 

 Canipsiinis decoloratns, penes and basal plate, dorsal view. G, Blastitrus ncbii- 

 losiis, ninth abdominal segment with styli and penes, ventral view. H, Iron 

 huiueralis, end of ninth abdominal sternum with styli and penes, ventral view. 

 I, Bactis z'acjajis, ninth abdominal sternum and styli, ventral view. J, Ephoron 

 lenkon, ninth abdominal sternum with styli and penis, ventral view. K, Camp- 

 siirus dccoloratus, ninth abdominal segment with styli and penes, ventral view. 

 L, Trichorythrodcs fallax, ninth sternum with styli and penis, ventral view. 

 M, Onicigasfer distaiis, larva, posterior part of abdomen, ventral view. 



b, stylus-bearing lobe of styliger (united coxopodites) ; c, median part of 

 styliger; Cer, cercus ; cf, caudal filament; cxmcl, muscles of coxopodite arising 

 on ninth abdominal sternum; Cxpd, coxopodite; DeJ, ductus ejaculatorius ; Eppt, 

 epiproct ; IXStii, ninth abdominal sternum; Papt, paraproct ; Pen, penisj pntcl, 

 muscles of basal arms of penis arising on ninth sternum; snicl, muscles of stylus 

 arising in coxopodite ; Sty, stylus ; x, basal arms or supporting plate of penes ; 

 XT, tenth abdominal tergum. 



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