The Nautilus. 



Vol. XIX. JUNE, 1905. No. 2. 



NEW TJNIONIDJS FROM ALABAMA. 



BY L. S. FRIER30N. 



Quadrula ar chert n. sp. Plate I, figs. 1, 2. 



Shell small, thin, lenticular, somewhat quadrate, smooth. An- 

 terior margin rounded, basal margin slightly curved, dorsal margin 

 somewhat bent midway, posterior margin rounded or bluntly pointed, 

 umbones low and flattened. Sides compressed, raised slightly at the 

 posterior angle, which is nearly obsolete ; posterior slope wide, and 

 somewhat elevated ; epidermis smooth, light brown, sometimes in- 

 clining to orange, two or three concentric bands of green or black 

 mark the earlier lines of growth. 



Teeth of the left valve double, anterior cardinal high, thin and 

 wedge-shaped, the posterior cardinal triangular, low and small, 

 laterals thin, rather short and nearly straight. 



In the right valve the cardinals are divided by a deep cleft, ex- 

 tending nearly to the bottom of the anterior adductor scar, the pos- 

 terior tooth being much the smaller. The dorsal plate is quite wide 

 for so small a shell. The shell cavity is quite capacious; the beak 

 cavities deep and compressed. Nacre white, with brown splotches, 

 and very iridescent. The nacre is probably also salmon-colored in 

 some individuals. The pallial line in the specimens before me is 

 nearly imperceptible in the posterior part of shell, where the nacre 

 is very thin. One specimen shows in the upper part of the shell 

 cavity, 20 or 30 almost microscopic muscle-scars extending from the 

 beak cavities half way to the pallial line. Long. 34, alt. 28, diam. 

 14 mm. Habitat : Tallapoosa River, at Tallassee, Ala. 



