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 cordata 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. 
Obovaria cordata Rafinesque, ’20, p. 312, pl. 82, pp. 6, 7. 
U. cordatus Raf. =U. obovata Raf. Conrad, ’34, p. 68 (obovata a 
mistake, possibly obovalis meant). 
Unio plenus Lea, ’40, p. 286. 
Quadrula plena (Lea) Simpson, ’14, p. 886. 
Quadrula cordata (Raf.) = Qu. plena (Lea) Vanatta, ‘15, p. 558 
(“type” examined). 
Pleurobema obliqum cordatum (Raf.) Ortmann, ’18, p. 548. 
Ob. cordata Raf. = Qu. plena (Lea) Walker, ’18¢, 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 Pleur, cordatum and Pilsbry’s 
note). Lea’s name plenus stands for this form. 
PLEUROBEMA CATILLUS (Conrad), 1836 
Type locality: Scioto River, Ohio. 
Unio catillus Conrad, ’36, p. 30, pl. 13, f. 2. 
Umio solidus Lea, ’38, p. 13, pl. 5, f. 13. 
U. coccineus Lea, ’37 =U. coccineus Con., ’36=U. cattllus Con.,, 
eae 3S, py isk 
Quadrula solida (ea), Simpson, ’14, p. 885. 
U. catillus Con. = Qu. coccinea (Lea), Simpson, ‘14, p. 884. 
Pleurobema obliquum catillus (Con.) =U. solidus Lea, Utterback, 
16, p. 79; Ortmann, 718, p. 548. 
Lea has pronounced U. catillus Con. to be identical with his 
(and Conrad’s) coccineus, and subsequent authors up to 
