loo Cincinnati Society of Natural History. 



25. Unio gibbosa, Barn. 



L. 2^ and more, H. 1^ or more. Nacre dark purple; when 

 white, called Unio arctior, Lea. Variety Unio camelus, 

 Lea, slopes more abruptly on posterior. 



26. Unio glans, Lea. 



L. H. Dark, finely rayed with black lines. 



27. Unio gouldiana, Ward. 



Like No. 10, but has white nacre. 



28. Unio granifera, Lea. 



L. 2^, H. 2^ and more. Nacre dark purple, two or more 

 rows of pustules, like No. 67. 



29. Unio iris, Lea. 



L. 2% or less, H. ij^ or less. Green finely rayed with dark 

 green lines. 



30. Unio irrorata, Zra. 



L. 2, H. 2. Pustules on lines of growth. Light green, finely 

 mottled with dark green points. 



31. Unio lacrymosa, Lea. 



L. 3 or more, H. 2^ or more. Pustules like tear drops, color 

 green. Variety Unio asperrima. Lea., has the pustules 

 more erect. 



32. Unio lens, Lea. 



Thick variety of No. 8. 



33. Unio luteola, Lam. 



L. 4^ or more, H. 2^ or more. Yellow beautifully rayed 

 with green. 



34. Unio metanevra, Raf. 



L. 2 or more, H. 2 or more. Like No. 31 but has no sulcus, 

 posterior ridge has large nodules. 



35. Unio multiplicata, Lea. 



L. 4^ or less, H. 3 or less. Posterior rectangular and very 

 much wringled. 



36. Unio multiradiata, Lea. 



L. 2^, H. 2. Ventricose and beautifully rayed with green. 



37. Unio obliqua, Lam. 



L. 2^, H. 2y 2 . Oblique, brown, faint rays below beaks. 



38. Unio occidens, Lea. 



Female of No. 58, shorter and more ventricose. 



