66 THE NAUTILUS. 



my former measurements, 0.22+0.28, do not differ much from 

 this. 



This species has a very characteristic shape, chiefly in the 

 female, with the postbasal part greatly expanded and obliquely 

 truncated. In old specimens, there is a more or less distinct 

 "constriction" in the middle of this truncation, making the 

 boundary between the branchial opening and the papillar part 

 of the mantle edge in front of it. This constriction corresponds 

 to that seen in the following species {E. constrida) , and shows 

 the close affinity of these two species. E. vnnuxemensis, in its 

 external aspect, is very similar to E. constrida, and when I 

 found these specimens at Saltville, I recognized them at once as 

 the representative form of E. constrida of the Roanoke and James 

 Rivers, with which I was quite familiar. However, the charac- 

 ter of the constriction, found rather regularly in old females of 

 constrida, is not so well developed in vanuxemensis, and I have 

 only a few old females of the latter, which show it distinctly. 



EuRYNiA (Micromya) constricta (Conrad) (See: Lampsilis c. 



Simpson, 1900, p. 551). 



Numerous specimens are at hand from the following localities: 

 Calf Pasture River, Goshen (May 11. 1912), North River, Lex- 

 ington and Buena Vista (June 7 and 8, 1912), all in Rockbridge 

 Co., Va. ; Jackson River, Covington, Allegheny Co. Va. (Aug. 

 11, 1911); Tinker Creek, Roanoke (June 10, 1912), Roanoke 

 River (.June 10, 1912) and Mason Creek, Salem (Aug. 13 ,1911); 

 these in the Roanoke drainage in Roanoke Co., Va. The spec- 

 imens collected on August 13 were gravid with eggs and one had 

 young glochidia; those collected in May and June had all glo- 

 chidia, when gravid, and on all dates discharging individuals 

 were found. Thus the breeding season begins in August and 

 ends in June. 



Supraanal separated from the anal by a moderately long man- 

 tle-connection, which is slightly shorter than either opening. 

 Anal finely crenulated. Branchial with papillae. In the fe- 

 male, the inner mantle-edge in front of the branchial is very 

 much like that of vanuxemensis ?ind arkansasensis: it is somewhat 

 lamellar and carries a number (10 to 12) of small, somewhat 



