72 Annals Entomological Society of America [Vol. XV, 



EXPLANATION OF PLATES. 



Plate L 



1. Machilis sp. (Machiloidea). Ventral view of terminal segments. 



2. Bias turns nebulosus Walk. (Ephemerida). Ventral view of terminal 



segments. 



3. Same, ventral view of penis. 



4. Callihaetis ferrngineiis Walsh. (Ephemerida). Ventral view of terminal seg- 



ments. 



5. Forficula auricularia L. (Dermaptera). Lateral view of terminal segments. 



6. Same, ventral view of penis. 



7. Anisolabis maritima (Gene). (Dermaptera). Ventral view of end of 



abdomen. 



8. Same, ventral view of penis. 



9. Oligotoma saiindersii Westw. (Embiidina). Dorsal view of end segments. 



r ap 10, 1 ap 10, right and left copulatory appendages of 10th tergum. 



10. Same, ventral view of end segments. Lettering as in Fig. 9. 



Plate IL 



11. Capnia vernalis Newp. (Plecoptera). Dorsal view of end segments. 



12. Same, ventral view of end segments. 



13. Same, lateral view of end segments. 



14. Isogenus frontalis Newm. (Plecoptera). Dorso-caudal view of end segments, 



the 10th and anal segments being somewhat upturned, sc, sac containing 

 stylets, formed by invagination of the supra-anal plate. The 10th tergum 

 is also divided into hemitergites by a median invagination, which forms a 

 ventral apodeme. 



15. Same; dorsal view of separated 10th and anal segments. The hemitergites 



of segment 10 are somewhat spread apart to expose the supra-anal plate, 

 m ap, apodeme formed by invagination of 10th tergum. 



16. Same, ventral view of isolated supra-anal plate, sc, sac containing the 



stylets and supported laterally by the paragenital plates. 



17. Same, lateral view of isolated supra-anal plate, together with ventral apodeme 



(m ap), formed by median invagination of 10th tergum. sc as in Fig. 16; 

 bb, basal bar connecting stylets with apodeme. 



18. Isoperla sp. (Plecoptera). Ventral view of end segments. The copulatory 



hooks are processes of the paraprocts. Segments 8 to 10 are annular, the 

 terga and sterna being fused. 



19. Perla tristis Hag. (Plecoptera). Ventral view of end segments, the 9th 



sternum partly cut away to show the penis. Copulatory hooks as in 

 Fig. 18. The 10th sternum is not separable from the interstemal 

 membrane. 



20. Same, ventral view of penis. 



21. Aeshna canadensis Walk. (Odonata). Ventral view of terminal segments. 



Plate III. 

 (Orthoptera — Tettigonoidea) . 



22. Ceuthophilus lapidicola Burm. Posterior view of penis with parameres 



retracted; fps, a temporary fold, formed by the retraction of the para- 

 meres and dividing the shallow spermatophore sac into an upper and 

 lower part, the upper part corresponding to th& paramere sac of most 

 Tettigonoidea (Figs. 30 and 32), and the spermatophore sac in the 

 Gryllidas; pmo, opening into the invaginated parameres. 



