UNIO 677 
subtruncated ; base line nearly straight ; anterior end slopingly 
cut away helow, rounded above; surface having more or less 
concentric sculpture, the sulcations strong at the anterior end: 
epidermis greenish-yellow, rayed, subshining; left valve with 
two subcompressed pseudocardinals and two club-shaped later- 
als; right valve with. two pseudocardinals, the upper small, and 
one lateral; muscle scars well marked, the posterior elongated ; 
nacre pale lurid brown. 
Length 69, height 30, diam. 15 mm. 
Type locality, Oconee River, Athens, Georgia. Also Abbe- 
ville, South Carolina. 
Unio sagittiformis Lea, Tr. Am. Phil. Soc., X, 1852, p. 277, 
Pi socmy 1 35 Obs, V, 1852, p. 63, pl xxi, fig. 35.— 
SOWERBY, Conch. Icon., XVI, 1868, pl. xcu, fig. 499— 
SIMPSON, Syn., 1900, p. 731. 
Margaron (Unio) sagittiformis Lea, Syn., 1852, p. 37; 1870, 
“pba. 
A peculiar shell, which may be diseased, yet it appears to 
be normal. The posterior point is much drawn out, the ante- 
rior base is decidedly cut away below. ‘The species might be 
placed in the fisherianus group with about as much propriety 
as in this. 
UNIo DISPALANS B. H. Wright. 
Shell subrhomboid, rather thin, subcompressed to convex, 
inequilateral; beaks not inflated or elevated, their sculpture 
consisting of strong ridges, which run parallel with the growth 
lines; posterior ridge well developed, narrowly rounded or 
angled, ending behind near the base in a blunt point or a fee- 
ble, narrow biangulation; anterior end a very little narrower, 
rounded ; surface with uneven growth lines; epidermis yellow- 
green and faintly rayed in young shells, brown, rough and 
cloth-like in old ones; pseudocardinals small, compressed, dou- 
ble in each valve, the upper in the right valve small; laterals 
delicate, curved ; muscle scars shallow; nacre dirty coppery. 
Length 65, height 35, diam. 18 mm. 
Type locality, Suwanee River, Florida. 
