THE NAUTILUS. 75 



flattened, with two dark inconspicuous lines running from beaks to 

 posterior margin, beak sculpture unknown ; cardinal teeth rather 

 long and solid, depressed, disposed to be double in both valves, cor- 

 rugate. Lateral teeth straight, oblique, corrugate. Anterior cicatri- 

 ces distinct, deep. Posterior cicatrices distinct and well impressed, 

 shell cavity wide and deep, nacre white. 



Habitat, near Poplar Bluff, Black River, Butler Co., Missouri. 



I know of no described species which this closely resembles ; in 

 outline it is perhaps nearest to U. Bigbyensis, Lea, but differs in 

 every other respect. Specimens of Bigbyensis from Flint River, 

 Ala., attain twice the size of this shell. Bigbyensis is nearly always 

 covered with green rays. This shell is rayless. It also has higher 

 and more massive beaks, is more equilateral and differs entirely in 

 the color of epidermis, teeth, etc. The color of the epidermis and 

 character of the beaks is more like U. Hartmanianus, Lea, but that 

 shell has very much higher beaks, more swollen and pointed, and is 

 in every respect a more solid shell. 



Four specimens of this shell from quite young to adult have been 

 in my collection for a number of years, having been collected by the 

 late Ellwood Pleas, of Ind. I never could place them with any 

 known species, but have kept them separate, hoping that sooner or 

 later I might obtain others like them, but having failed to obtain 

 others, I now describe them. 



A NEW UNIO FBOM TEXAS. 



BY L. 8. FRIERSON. 



Quadrvla lananensis, n. sp. Plate IV. 



Shell quadrate to triangular, nearly equilateral, anterior margin 

 rounded. Base round in front, nearly straight behind. Posterior 

 oblique, biangular, slightly emarginate. Dorsum curved, smooth, 

 nearly polished above, striate below and upon posterior slope. Lines 

 of growth distinct and ill-defined. Dark reddish-brown, sometimes 

 a little olive, obscurely radiate. Beaks eroded, umbos low, some- 

 what inflated. Anterior umbonal slope rounded. Lateral slope flat- 

 tened. Posterior ridge angular near the beaks, becoming obsolete 

 near the base. Ligament brown, smooth, medium-sized. 



