﻿24'^ M!:i)K)M!)l'S 



Unio conrodhis Conuai;. Monog.. X. 1838. p. 87. pi. xi.vii. 



fi?. 3- 

 Mari^oron (Unio) conradianus Lka, Syn., 1870, p. 32. 

 Unio conradianus l>. 11. Wuh'.ht. Check List, 1888. 



A^erv closely allied to the followinj:^, but it has a smoother 

 shell, a less developed posterior ridtj:c and is more rounded 

 posteriorly. 



Medionidus i'.\kvui,us (Lea). 



Shell small, elongated. subcomi>ressed. subsolid. somewhat 

 rhomboid, with a low. rounded {posterior ridge, above whicli 

 it is corrugately ])licate; in front of it the surface is smooth: 

 beaks moderate, their sculpture not seen ; surface greenish or 

 vellowish. marked with delicate, green, undulating or zigzag 

 lines, which sometimes form very faint rays ; pseudocardinals 

 small and with the laterals much as are those of the other 

 species of the group ; nacre bluish-green. 



Ivcngth 40. height 20, diam. 11 mm. 



Coosa River, Alabama : Chattanooga and vSwamp creeks, 

 northwest Georgia. 



Type locality, Coosa River, Ala. ; Chattanooga, Georgia. 

 Unio parvidus Lea, Pr. Ac. N. Sci. Phila., IV, i860, p. 307; 



Jl. Ac. N. Sci. Phila., VL 1866, p. 45, pi. xvi. fig. 43 ; Obs., 



XL 1867, p. 49. pi. XVI, fig. 43. 

 Mari^aron (Unio) parrulns Lka, Syn.. 1870, p. 32. 

 Mcdiouidiis parrulus Simpson, Syn.. Kpo, p. 590. 



A doubtful species, but T can hardly connect it with any of 

 the others. It may be a variety of the conradiciis, but it is 

 smoother, diiTerently colored and more delicate. All the shells 

 I have seen are females and are slightly produced near the 

 center of the base. The posterior point is somewhat raised 

 above the basal line. 



Mediontdus PENiciLEATus (Lea). 



Shell small, long rhomboid, subinflatcd, subsolid, inequilat- 

 eral ; beaks scarcely elevated, their sculpture -not seen : poste- 

 rior ridge moderately developed, rounded in the adult state. 



