/ 



fHE Nautilus. 



Vol,. XVTII. DECEMBER, 1904. No. 8. 



NEW FORMS OF POLYGYRA FROM ALABAMA. 



BY GEORGK H. CLAPP. 



Polygyra {Steiiotrema) barhata n. sp. 



At first glance this species would be readily taken for P. sfeno- 

 trema and as it may exist in some collections under that name it can 

 best be described by comparison with that well-known and widely 

 distributed species. 



Viewed from above, the difference is at once apparent, as barbala 

 has stiff hairs about ^ mm. in length which are widely spaced, and 

 the diagonal series cross the lines of growth at nearly a right angle. 

 The upper half of the outer lip is well reflected, not appressed as in 

 steiiotrema and there is a distinct constriction l)ack of it. From below 

 the difference is still more striking, a^ the width of the mouth in harbutd 

 \s U\\\y double that of stenotrema ; in barbata the wi<lt!i, measured 

 from the top of the tooth to the edge of the lip just below the notch, 

 is 1 mm., while in a steiiotrema of tlie same size it is only about ^ mm. 

 The lamellitorni tooth is more sinuous and le.ss massive. The flat- 

 tened upper lip, which is markedly concave, has a well pronounced 

 tooth just opposite the up|)er end of the abruptly truncated parietal 

 tooth. The " fulcrum," which is plainly visible through the shell, is 

 the most pronounced feature, as it is 3 mm. in length, extending from 

 the axis fully half way across the body-whorl. Embryonie whorls 

 polished and obsoletpjy ribbed, while in sleiio'rcma they are graimla- 



