92 ILLINOIS BIOLOGICAL MONOGRAPHS [286 



EXPLANATION OF PLATE 



Fig. 25. — Reproductive organs of Dalyellia megacephala; X about 200. 



Fig. 26. — ^Protonephridium of Dalyellia alba; X about 340. 



Fig. 27. — Rhabdites of Typhloplana viridata, one in cell. Camera lucida; X 350. 



Fig. 28. — Eyes of Strongylosloma rosaceum; X about 200. 



a. Lateral surface of eye; X about 200. 

 Fig. 29. — ^Tail region of Mesostoma angulare; X about 100. 

 Fig. 30. — Rhabdites of Typhloplana viridata. Camera lucida; X 350. 

 Fig. 31. — Rhabdites of Typhloplana viridata, old cell; X about 300. 

 Fig. 32. — Tail region, Mesostoma simplex; X about 100. 

 Fig. 33. — Rhabdites in cell, Mesostoma simplex. Camera lucida; X ISO. 

 Fig. 34. — Mesostoma simplex, vitelline gland cell, showing stored oil globules; X about 250. 

 Fig. 35. — Ovary of Mesostoma simplex; X about 350. 

 Fig. 36. — Cirrus sac, Mesostoma simplex; X about 350. 

 Fig. 37. — Testis, Mesostoma simplex; X about 350. 

 Fig. 38. — Rhabdites in cell, Mesostoma simplex; X about 200. 

 Fig. 39. — Eye, Dalyellia megacephala; X about 175. 

 Fig. 40. — End view of rhabdite-bearing cell of Mesostoma simplex; X about 350. 



