68 University of Michigan 
55-5 x 26.5 mm.; ‘pew epats’ would alone throw it out.” (H- 
AGS) 
Subgenus SCALENILLA n. n. 
Type: Unio sulcatus Lea. 
Scalenaria Rafinesque, ’20, p. 309 (no type named) ; Herrmannsen, 
"48, p. 422 (type, Obliquaria scalenia Raf.) ; Agassiz, ’52, p. 43 (no 
type named) ; Simpson, ‘00, p. 519 (type, Unio sulcatus Lea). 
The type of Scalenaria has been designated by Herrmann- 
sen as Oblig. scalenia Raf., which is the same as Pleurobema 
clava (Lam.), which see. Thus this name becomes a synonym 
of Pleurobema. Subsequent attempts by Agassiz (first spe- 
cies) and Simpson to select, as type Obliq. obliquata Raf. (an. 
unidentifiable species) or U. sulcatus Lea (supposed to be 
the same as obliquata) are invalid. Since there is no avail-— 
able name for this subgenus, we propose that of Scalenilla. 
DysNOMIA (SCALENILLA) SULCATA (Lea), 1829 
Type locality: Ohio, 
Obliquaria (Scalenaria) obliqtata Rafinesque, ’20, p. 309 (Kentucky 
River). 
Unio sulcatus Lea, “May or June,’ 1829 (not 730, as given by Simp- 
son); p. 430, ‘pl. °8,. t. 12. 
Unio ridibundus Say, October 7, 1820, p. 308. 
U. obliquatus Raf.= U. sulcatus Lea, Conrad, °34, p. 70. 
U. obliquatus Raf.—=U. sulcatus Lea = U. haysianus Lea =U, ridi- 
bundus Say, Ferussac, 35, pp. 28, 34. 
Scalenaria obliquata (Raf.) = U. sulcatus Lea (male) = U. ridibun- 
dus Say (female), Agassiz, °52, p. 43. 
Truncilla (Scalenaria) sulcata (lea), Simpson, ’14, p. 14. 
Trunc. obliquata (Raf.) =Tr. sulcata (Lea), Vanatta, ’15, p. 550+ 
(“type” examined). 
Tr. sulcata (Lea) = Ob. obliquata Raf., Walker, ’16°¢, p. 45, and ’18¢,. 
p. 186 (“if identifiable”). 
U. sulcatus Lea is not preoccupied by Pleurobema cuneata 
sulcata Raf. ((20), as Vanatta claims (see Walker). 
Obl. obliquata is not identifiable from the original descrip-- 
