Occasional Papers of the Museum of Zoology 39 



Alasmidonta (Rugifera) tnmcata (Wright), Simpson, 'oo", p. 671. 



Alasmidonta vmrgiu-afa (Say), Simpson, '01, p. 16 (Scioto River) ; 

 Fox, '01, p. 47 (Scioto River, Chillicothe, Ohio). 



Alasmidonta (Rugifera) marginata (Say), Simpson, '14, p. 505. 



Alasmodon scriptum Raf. ^,4. marginata Say, Frierson, '14", p. 7. 



Alasmodon atropurpurcnm Raf., '31 ^ Margaritatm ravencliana Lea, 

 '34; Frierson, '14", p. 7. 



Alasmidonta (Dectirainbis) marginata (Say), Ortmann, "iS, p. 561. 



There is no doubt as to the priority of marginata Say, but 

 the identification of scriptum and atropiirpureitm is important 

 with regard to the validity of the subgeneric name Decurambis. 



In A. scriptum, the posterior truncation, nearly flat, with 

 transverse furrows and ribs, and the color of the epidermis as 

 described, make it positive that A. marginata Say was intended. 

 Thus scriptum is recogtiizable. and the subgenus Decurambis, 

 in which it stands, is valid (see above). 



This makes it unnecessary to identify A. atropurpurcnm Raf. 

 According tc Frierson, this is the same as ravencliana Lea, 

 but Ortmann ('18) has shown that specimens taken for atro- 

 purpurcum are not ravcnclianum, but a form (varietv or varia- 

 tion) of marginata. But the correct identification of those 

 specimens is not yet assured, and for the present atropur- 

 purcum is an unidentified form. 



Alasmidonta (Decurambis) varicosa (Lamarck), 1819 

 Type locality: Schuylkill River, Philadelphia, Pa. 



Unio varicosa Lamarck, '19. p. 78 (Schuylkill River). 



Alasmodonta marginata Say. '19 (Scioto River). 



U. varicosa ham. =: Alasmodonta undulafa Say, Lea, '29, p. 424; 

 Ferussac, '35, p. 26. 



U. varicosa hs.m.^^ Alasmodonta marginata Say, Lea, '34, p. 91 

 (type examined). 



Alasmodon corriigata DeKay, '43, p. 198, pi. 24, f. 259. 



Alasmidonta {Rugifera) marginata (Say), Simpson, '99<^, p. 670. 



Alasmidonta marginata (Say), Simpson, '01, p. 16 (Scioto River); 

 Fox, '01, p. 47 (Scioto River, Chillicothe, Ohio). 



