298 THOMAS SAY FOUNDATION 



PLATE 4. 



Genitalia of Plecoptera. 



Acroneuria arenosa Pict., end of abdomen of $ , dorsal view. 

 Acroneuria arenosa Pict., end of abdomen of $ , ventral view. 

 Acroneuria arenosa Pict., end of abdomen of $ , lateral view. 

 Acroneuria arenosa Pict., end of abdomen of $ , ventral view: 



gh, genital hooks; h, hammer; e, eggs. 

 Acroneuria arenosa Pict., a genital hook removed, and enlarged. 

 Perlodes signata Hag., end of abdomen of $ , lateral view, with 

 supra-anal process (s) elevated and penis protruded; the 

 segments are numbered 7, 8, 9 and 10; t, tail; l.s. lateral 

 stylet of the supra-anal process; tl. titillator of the penis. 

 Fig. 7. The detached 9th segment of the same. 

 Fig. 8. The detached 10th segment of the same. 



Fig. 9. The detached supra-anal process of the same, b, the basal mid- 

 dorsal attachment plate; Is, lateral stylet; m, membranous 

 flap. 

 Fig. 10. The detached subanal plate (sub. a) bearing the tail (/.). 

 Fig. 11. Acroneuria pacifica Bks., end of abdomen, lateral view. 

 Fig. 12. Acroneuria pacifica Bks., with penis protruded. 

 The Acroneuria drawings are by Miss M. J. Fisher. 

 The Perlodes drawings are bv Miss Hazel E. Branch. 



