NO. 1205. SYNOPSIS OF THE NAIADES SIMPSON. 743 



* t UNIO OBESUS var. PALUDICOLUS Gould. 



* Unio paludicolus GOULD, Pr. Bost. Soc. Nat. Hist., II, 1845, p. 53. * GOULD, 



Otia. Couch., 1852, p. 197.* H. and A. ADAMS, Gen. Rec. Moll., II, 1857, 

 p. 493. * B. H. WRIGHT, Check List, 1888. 



* Margaron ( Unio) paludicolus LEA, Syri., 1852, p. 33; 1870, p. 54. 



* f'niopaludicolor CONRAD, Pr. Ac. N. Sci. Phila.,VI, 1853, p. 254. *P,fcTEL, Conch. 



Sam., Ill, 1890, p. 162. 



Southern Virginia southward in streams draining into the Atlantic, 

 and throughout the peninsula of Florida. 



tUNIO BISSELLIANUS Lea. 



* Unio bissellianus LEA, Pr. Ac. N. Sci. Phila., XI, 1867, p. 81; * Jl. Ac. N. Sci. 



Phila., VI, 1868, p. 277, pi. xxxvn, fig. 90; * Obs., XII, 1869, p. 37, pi. 

 xxxvn, fig. 90.* B. H. WRIGHT, Check List, 1888.* PJETEL, Conch. Sam., 

 Ill, 1890, p. 146. 



* Margaron (Unio) Mssellianus LEA, Syn., 1890, p. 50. 



BisselFs Pond, Charlotte, North Carolina. 



tUNIO SUBLURIDUS Simpson. 



* Unio suUuridus SIMPSON, Pr. U. S. Nat. Mus., XV, 1892, p. 432, pi. LXXIII, figs. 



3,4. 



Orange Springs, Marion County, Florida. I can not be certain as to 

 the relationship of this species, as the beaks are eroded in the only 

 shells I have seen. 



Section MICRONAIAS Simpson, 1900. 

 (Type, Unio aratus Lea. ) 



Shell small, oval, a little produced near the posterior base, with a 

 moderate posterior ridge and pointed near the base behind ; beaks 

 rather prominent, the sculpture being apparently rather fine, irregu- 

 larly concentric ridges, having a tendency to fall into two loops 5 the 

 whole surface strongly and closely concentrically ridged; pseudocardi- 

 nals compressed, high, slightly curved upward; laterals compressed, 

 curved; beak cavities moderately deep; nacre whitish; anterior muscle 

 scars deep, rough; posterior well marked. 



Animal with the marsupiuin pad-like, occupying all but the extreme 

 posterior part of the outer gills ; branching elongated, wider behind, inner 

 the larger throughout, free from the abdominal sac or united to it; 1 

 palpi large, rounded behind; mantle with thickened border; anal 

 opening crenulate. 



1 In some specimens free throughout; in others entirely united. 



