Occasional Papers of the Museum of Zoology 45. 
OBOVARIA RETUSA (Lamarck), 1819 
Type locality: (Incorrectly given as Nova Scotia). 
Unio retusa Lamarck, ’19, p. 72. 
Obovaria torsa Rafinesque, ’20, p. 311, pl. 82, f. 1-3. 
U. retusa Lam.= U. torsus Raf., Lea, ’34, p. 88 (type examined) ; 
Herussac;’ 35, p: 205) Conrad, 36; p. 10; pl. 8: 
Obovaria retusa (Lam.) = U. torsa Raf., Agassiz, ’52, p. 46. 
Obovaria retusa (Lam.), Simpson, ’14, p. 290. 
O. retusa, Clam:)' =O. torsa Raf. Vanatta; 715, “p. 552. (type” 
examined). 
Lamarck’s original description is, in spite of the incorrect 
locality given (Nova Scotia), perfectly recognizable. The 
rounded, swollen shell, with incurved beaks, and the violaceous 
nacre is unmistakable. 
Rafinesque’s torsa is also undoubtedly this, and his figures 
give fairly well the general character of the species. 
OBOVARIA SUBROTUNDA (Rafinesque), 1820 
Type locality: Ohio River. 
Obliquaria subrotunda Rafinesque,’’20, p. 308, pl. 81, f. 21-23. 
Obovaria striata Rafinesque, ’20, p. 3IT. 
Unio circulus Lea, ’29, p. 433, pl. 9, f. 14. 
U. subrotundus Raf.=U. pusilla Raf.=U. striata Raf. =U. cir- 
culus Lea, Conrad, 734, p. 71. 
U, subrotundus Raf.=U. circulus Lea, Ferussac, ’35, p. 28. 
Obovaria circulus (Lea), Simpson, 14, p. 201. 
Ob. subrotunda (Raf.) =Ob. striata Raf.=Ob. circulus (Lea),. 
Vanatta, “15, p. 552 (“‘type” examined). 
Obovaria subrotunda (Raf.), Ortmann, °18, p. 567. 
Obl. circulus (Lea) = OdI. subrotunda Raf., Walker, ’18¢, p. 180 
(“if identifiable”). 
Rafinesque’s description and figures indicate a rather thick, 
nearly round, swollen shell, with beaks almost central (“equi- 
laterale’), brownish-yellow epidermis, and _ whitish-purple 
nacre. A shell from the Ohio with these characters will be 
easily recognized as the circulus Lea. Thus subrotunda is. 
