purplish; cardinal teeth thick, direct; lateral teeth 

 thick. 



OBSERVATIONS. 



On a passing glance this shell would certainly be 

 mistaken for U. ?iasutus, but the thickness of the shell, 

 the dilated anterior side, and thick, direct, lateral 

 teeth, will sufficiently distinguish it. The disk pos- 

 teriorly has several small plicae or undulations simi- 

 lar to those of U. grayanus, Lea, but as only one 

 specimen can be examined this character may prove 

 inconstant. 



In the cabinet of Mr. Phillips. I found it on the 

 shore of Savannah river, at Augusta, and supposed 

 it to be a variety of nasutiis, but comparing it with 

 that species from South Carolina and Florida, it was 

 found to differ materially, and to form a link between 

 it and the rectus. 



UNIO LANCEOLATUS. 



Plate XIV.— Fig. 2. 



DESCRIPTION. 



Shell narrow-elliptical, thin, ventricose, yellowish, 

 smooth and polished; disks slightly flattened; ante- 

 rior side somewhat compressed, not very short, mar- 

 gin regularly rounded; umbonial slope regularly 

 rounded, inflated; posterior side produced, extremity 



