41 



UNIO ICTERINUS. 



Plate YL—Pig. 5. 



DE SCRIPTION. 



Shell elliptical, moderately thick; anterior margin 

 regularly rounded; posterior margin descending 

 obliquely, and subtruncated at the extremity; beaks 

 not prominent; umbonial slope very oblique, nearly 

 rectilinear, angulated; epidermis smooth and polish- 

 ed, olive yellow, clouded with brown on the margins; 

 base slightly arcuated; nacre salmon coloured, iri- 

 descent on the posterior margin. 



OBSERVATIONS. 



A species approaching that variety of U.piirpureiis, 

 of Say, termed carinatus, by Lamarck; but I believe 

 it to be quite distinct. It certainly does not resemble 

 the purpureiis of the same locality. 



Whilst at Augusta in the month of February, when 

 the Savannah river had risen considerably above low 

 water mark, I found on the muddy shore opposite 

 the town, numbers of Unios, which had been recently 

 taken by the muskrats. Amongst these were the 

 two species mentioned above, U. angustatus, of 

 Lea, abundance of U. congarceus, Lea, a remark- 

 able variety of U. nasutus, Say, thick, and salmon 

 coloured within; and a suborbicular species, very 

 distinct from any other species I have seen. All the 

 specimens of icterimis are more or less salmon co- 

 D 2 



