Occasional Papers of the Museum of Zoology 39 
Alasmidonta (Rugifera) truncata (Wright), Simpson, ’oo°, p. 671. 
Alasmidonta marginata (Say), Simpson, ’o1, p. 16 (Scioto River) ; 
Fox, ’o1, p. 47 (Scioto River, Chillicothe, Ohio). 
Alasmidonta (Rugifera) marginata (Say), Simpson, ’14, p. 505. 
Alasmodon scriptum Raf.— A. marginata Say, Frierson, ’14*, p. 7. 
Alasmodon atropurpureum Raf., °31 = Margaritana raveneliana Lea, 
34.5 Firterson, “L4°;) p.,"7; j 
Alasmidonta (Decurambis) marginata (Say), Ortmann, ’18, p. 561. 
There is no doubt as to the priority of marginata Say, but 
the identification of scriptum and atropurpureum 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 sceriptwm is recognizable, and the subgenus Decurambis, 
in which it stands, is valid (see above). 
This makes it unnecessary to identify A. atropurpureum Raf. 
According to Frierson, this is the same as raveneliana I.ea, 
but Ortmann (18) has shown that specimens taken for atro- 
purpureum are not ravenelianum, but a form (variety or varia- 
tion) of marginata. But the correct identification of those 
specimens is not yet assured, and for the present atropur- 
pureum is an unidentified form. 
ALASMIDONTA (DECURAMBIS) VARICOSA (Lamarck), 1819 
Tv pe locality: Schuylkill River, Philadelphia, Pa. 
Unio varicosa Lamarck, ‘19, p. 78 (Schuylkill River). 
Alasmodonta marginata Say, “19 (Scioto River). 
U. varicosa Lam.= Alasmodonta undulata Say, Lea, ’20, p. 424; 
Ferussac, ’35, p. 20. 
U. varicosa Lam.= Alasmodonta marginata Say, Lea, '34, p. 91 
(type examined). 
Alasmodon corrugata DeKay, ’43, p. 198, pl. 24, f. 259. 
Alasmidonta (Rugitfera) marginata (Say), Simpson, ’99°, p. 670. 
Alasmidonta marginata (Say), Simpson, ’or, p. 16 (Scioto River) ; 
Fox, ’o1, p. 47 (Scioto River, Chillicothe, Ohio). 
