50 Univcrsily of Michigan 



Truxcilla truxcata Rafinesque, 1820 

 Type locality: Ohio River. 



Truncilla truncata Rafinesque, '20, p. 301. 



Unio elegans Lea, '31, p. 83, pi. 9, f. 13. 



U. truncatus Raf. ^ L'. donaciformis Lea, '28 = L\ elegans Lea, 

 Conrad, 34, p. 72. 



U. truncatus Raf. = U. elegans Lea, Ferussac, '35, p. 27. 



Plagiola elegans (Lea), Simpson, '14, p. 307. 



PI. elegans (Lea) = T'r. truncata Raf. = L'. inetaplata Raf., '31; 

 Vanatta, '15, p. 553 ('"types" examined). 



PI. elgeans (Lea) = Tr. truncata Raf., Walker, '16^, p. 45; 'i8'", 

 p. 179 ("if identifiable"). 



Antygdalouaias truncata (Raf.), Utterback, '16, p. 148; Ortmann, 

 '18, p. 570. 



Thi.s shell is small, has a "semi-triangtilar," somewhat quad- 

 rate shape, the posterior end is truncate, and the margin and 

 growth lines (rides) are curved (concave) behind. This is 

 a satisfactory description of the species when compared with 

 the only other ''truncate'' form of the Ohio (triquetra). 



U. donaciformis Lea, said to be also identical (Conrad), is 

 closely allied, but the description of the shape does not fit it. 



The name Truncilla truncata is not preoccupied by Unio 

 triDicata Spengler (1793), and thus truncata stands. 



TRUXC11.LA DOXACiFORMis (Lea), 1828 



Type locality: Ohio. 



Unio nervosa Rafinesque, '20, p. 296, pi. 80, f. 8-10. 

 Unio donaciformis Lea, '28, p. 267, pi. 4, f. 3. 

 Unio zigzag Lea, '29, p. 440, pi. 12, f. 19. 

 U. nervosa Raf. = U. donaciformis Lea, Say, '34. 

 U. nervosa Raf. = U. zigzag Lea, Conrad, '34, p. 70. 

 U. nervosa Raf. =: U. zigzag Lea, Ferussac, '35, p. 27. 

 Plagiola donaciformis (Lea), Simpson, '14, p. 308. 



The original description of the rays of nervosa, "Nervures 

 Hexueuses, concentriques, ■vcrmiculaires," might suggest U. 

 donacifonnis, yet it surely is not quite exact, and the figure. 



