Occasional Papers of the Museum of Zoology 23 



and both introduced before Lea had established the identity 

 of U. obliqua Lam. No selection has been made by previous 

 authors, and thus we are at liberty to select cordafa as the 

 specific name. This corresponds to the recommendation made 

 in the Code, Art. 28, C : "A specific name accompanied by 

 both description and figure stands in preference to one accom 

 panied only by a diagnosis." 



PlEurobema plenum (Lea), 1840 

 Type locality: Ohio River, Cincinnati, Ohio. 



Ohovaria cor data Rafinesque, '20. p. 312, pi. 82, pp. 6. 7. 



U. cordatus Raf. = t^ ohovata Raf. Conrad, '34, p. 68 (obovata a 

 mistake, possibly obovalis meant). 



Unio plcnns Lea, '40, p. 286. 



Quadrula plena (Lea) Simpson, '14, p. 886. 



Quadrula cordata (Raf.) = On. plena (Lea) Vanatta, '15, p. 55S 

 ("type" examined). 



Pleuropcma obliqum cordatum (Raf.) Ortmann. '18, p. 548. 



Ob. cordata Raf. = ();(.. plena (Lea) Walker, 'i8c, p. 168 ("if iden- 

 tifiable"). 



Rafinesque's name cordata cannot be revived for plenus Lea, 

 since the original description and figure directly contradict 

 this approximation (see under Plcnr. cordatum and Pilsbry's 

 note). Lea's name plcnns stands for this form. 



PlEurobema catillus (Conrad), 1836 

 Type locality: Scioto River, Ohio. 



Unio catUlus Conrad. 36, p. 30. pi. 13, f. 2. 

 ■ Unio solidus Lea, '38, p. 13, pi. 5, f. 13. 



U. coccmeus Lea, '27^=^- coccin<cus Con., "36=1'. catillus Con., 

 Lea, '38, p. 131. 



Quadrula soUda (Lea). Simpson, '14, p. 885. 



U. catillus Con. = (3u. coccinca (Lea), Simpson, '14, p. 884. 



Pleurobcma obUquum catillus (Con.) = f/. solidus Lea, Utterback, 

 '16, p. 79; Ortmann, '18, p. 548. 



Lea has pronounced U. catillus Con. to be identical with his 

 (and Conrad's) coccinens, and subsequent authors up to 



