68 University of Michigan 



55.5 X 26.5 mm. ; 'pcu epais' would alone throw it out." (H^ 

 A. P.) 



Subgenus Scale;nii^i,a n. n. 



Type: Unio siilcatus Lea. 



Scalcnaria Rafinesque, '20, p. 309 (no type named) ; Herrmannsen, 

 '48, p. 422 (type, Obliqiiaria scalenia Raf.) ; Agassiz, '52, p. 43 (no- 

 type named) ; Simpson, '00, p. 519 (type, Unio sulcatus Lea). 



The type of Scalcnaria has been designated by Herrmann- 

 sen as Obliq. 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 j or U. sulcatus Lea (supposed to ba- 

 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 (Scalcnaria) obliquata Rafinesque, '20, p. 309 (Kentucky.- 

 River). 



Unio sulcatus Lea. "May or June," 1829 (not '30, as given by Simp- 

 son), p. 430, pi. 8, f. 12. 



Unio ridibundus Say, October 7, 1829, p. 3(^. 



U. obliquatus Raf. = U. sulcatus Lea, Conrad, '34, p. 70. 



(/. obliquatus Raf. = U. sulcatus Lea = U. haysianus Lea = U. ridi- 

 bundus Say, Ferussac, '35, pp. 28, 34. 



Scalcnaria obliquata (Raf.) =^ U. sulcatus Lea (male) = U. ridibun- 

 dus Say (female). Agassiz, "52, p. 43. 



Truucilla (Scalcnaria) sulcata (Lea), Simpson, '14, p. 14. 



Trunc. obliquata (Raf.) = Tr. sulcata (Lea), Vanatta, '15, p. 550- 

 ("type" examined). 



Tr. sulcata (Lea) =z Ob. obliquata Raf.. Walker, 'i6c, p. 45, and 'i8c,, 

 p. 186 ("if identifiable"). 



U. sulcatus Lea is not preoccupied by Pleurobema cuneata 

 sulcata Raf. ('20). as Vanatta claims (see Walker). 



Obi. obliquata is not identifiable from the original descrip— 



