128 A nnals Entomological Society of A nierica [ Vol . II, 



Scott, J. On certain Genera and Species of the Group of Psyllidae in the col- 

 lection of the British Museum. 1882. Trans. Ent. Soc. London. 1882. 

 pp. 449-473. Plates XVIII, XIX. 



Scudder, S. H. Fossil Insects. 



Vickery, R. A. A Comparative Study of the External Anatomy of Plant Lice. 

 19()S. 



Woodworth, C. W. The Wing Veins of Insects. 1906. 



EXPLANATION OF PLATES. 



The figures submitted have been selected from numerous ones prepared 

 in the progress of this study. In their preparation two methods were employed. 

 The figures showing tracheation are from camera lucida sketches verified or 

 corrected by examination of each significant point through a high power lens, — 

 oil emersion when necessary. The figures giving venation (except Fig. 29) are 

 ink tracings of photographs, — the blue prints which were used being bleached 

 after the drawings were made in order that black and white figures uniform with 

 the camera lucida sketches might be secured. 



PLATE XVI. 



Fig. 1. Lachnus strohi (Fitch). Tracheation of wing of newly emerged 

 aphid. Seepage 111. 



Fig. 2. M danoxanthus sp. Wing of newly emerged individual showing 

 an unusual case of coalescence of trachete, See page 107. 



Fig. 3. Myzus cerasi (Fab.) Tracheation of wing of newly emerged 

 aphid. See page 110. 



Fig. 4. Aphis species. Tracheation of wing of newly emerged aphid 

 showing connection with the body trachea. The region of the costal vein and 

 also the main vein channel of the wing indicated here. See page 108. 



Fig. 5. Callipterus idniifolii Monell. Tracheation of wing of newly emerged 

 aphid. 



Fig. G. Chaitophoriis nigrcc Oestlund. Tracheation of wing of newly 

 emerged aphid. See page 116. 



Fig. 7. Chaitophoriis popiilicola Thos. Tracheation of hind wing of newly 

 emerged aphid. Typical, showing connection with body trachea. See page 116. 



Fig. 8. Macrosiphum solanifolii Ashmead. Venation of both wings. 



Fig. 9. Macrosiphum pisi. Tracheation of hind wing of newly emerged 

 aphid. Very exceptional. See page 116. 



PLATE XVII. 



Fig. 10. Microparsus variabilis Patch. Venation of both wings. Vena- 

 tion of this species very unstable. The type figured is a common one. 



Fig. 11. Toxo ptera graminiim Hond. Venation of both wings. 



Fig. 12 and 13. Pemphigus acerifolii Riley. Tracheation of fore and hind 

 wings of newh^ emerged aphid. See pages 109 and 117. 



Fig. 14. 'Pemphigus venafuscus Patch. Venation of both wings. 



Fig. 15. Hamamclistes spinosiis Shimer. Tracheation of wing of newly 

 emerged aphid. See page 114. 



Fig. 16. Hamamclistes spinosiis Shimer. Venation of both wings. 



Fig. 17. Tetrancura sp. Venation of both wings. 



PLATE XVIII. 



Fig. 18. Mindariis {abietinus Koch ?). Tracheation of wing pad of 

 nj'mph. See page 115. 



Fig. 19. Mindarus {abietinus Koch ?). Tracheation of freshly emerged 

 wing. 



Fig. 20. Mindarus {abietinus Koch ?). Venation of both wings. See 

 page 114. 



Fig. 21. Schizoneura rileyi Thomas. Tracheation of wing pad of nymph. 

 See page 114. 



Fig. 22. Schizoneura rileyi Thomas. Tracheation of freshly emerged 

 wing. See page 114. 



Fig. 23. Schizoneura americana Riley. Venation of both wings. 



