﻿ALASMIDONTA S^O 



r.aphia holstonia H. and A. Adams, Gen. Rec. Moll, II, 1857, 



p. 499. 

 Alasmidotita holstonia Simpson, Syn., 1900, p. 670. 

 Unio Iwlstonianus Hanley, Biv. Shells, 1843, p. 213, pi. xxii, 



fig. 44.— SowERiJY, Conch. Icon., XVI, 1868, pi. lxxvi, fig. 



398. 

 M^argaritana holstoiiiaiia Kuster, Conch. Cab. Unio. 1862, p. 



302, pi. c, fig. 4- 

 / Unio striatus Sov;ekrv. Conch. Icon.. X\"I, 1808. pi. Lxxviii, 



fig. 407. 



A small species without any striking characters. It looks 

 so much like a member of the vanuxemensis group of Lamp- 

 silis that it has often deceived experts and has been sent oiit 

 as Unio lltns, U. proprius, etc.. but a glance at its interior will 

 always show the lack of laterals, which are present in the other 



species. 



Group of Alasmidonta georgiana. 



Shell rhomboid, slightly rayed, with strong beak sculpture, 

 the ridges parallel with the growth lines ; pseudocardinals sin- 

 gle, in each valve ; laterals wanting. 

 Alasmidonta georgiana (Lea). 



Shell elliptical, convex, rather thin, inequilateral, beaks al- 

 most compressed, not elevated but pointed, their sculpture con- 

 sisting of a few rather coarse ridges, which run nearly paral- 

 lel to the growth lines; posterior ridge full, rounded, ending 

 behind in a rounded point below the median line; growth 

 lines irregular; epidermis dirty yellowish-green with a few 

 narrow rays behind or rayless ; left valve with a low, smooth, 

 compressed tooth just in front of the beak; right valve with a 

 single compressed tooth placed well forward ; laterals reduced 

 to mere vestiges ; nacre bluish or purplish, dirty and lurid. 



Length 53, height 30, diam. 17 mm. 



Type locality, Etowah River, Georgia. Also Tennessee. 

 Mari^aritana etowahensis Lea, Pr. Ac. Xat. Sci. Phila.. 11. 

 1858. p. 138: Jl. Ac. Xat. Sci. Phila., 1\'. 1850. p. 227, pi. 

 xx^xi, fig. iio;"()bs.. VII, 1859. p. 45. Pl- -'^-^-^r' ^S- i lO- 



