THE NAUTILUS. 21 



rounded whorls and a less distinctly plicate columella. There is also 

 an umbilical chink, which is usually absent in catascopium. 



Like Walker's Lymvaa haheri from Michigan, nashotahensis is 

 apparently an extinct species peculiar to marl deposits. The speci- 

 mens were secured by Mr. F. M. Woodruff. 



NOTES ON PLANORBIS II: P. BICAKINATTIS. 



BY BRYANT WALKER. 



(Concluded from May Number.) 



IX. Miscellaneous. 



In Beck's Index Moll. (1837), p. 118, the following synonymy of 

 this species is given : 



'■'■ Planorhis hicarinatus Say. Am. Septr. C. C. 



a. major. S. g. iv, 4. W. S. vii, 12. Fl. Schuylkill. 



PI. angidatus Wood. 



b. minor. 



an P. ehurneus Ch. ix, 1123? New Jersey." 

 P. angidatus Wood, Index Testaceologicus, edit. II, 1828, Suppl., 

 pi. 7, f. 12, is a typical P. bicarinatus. The figures in Sowerby's 

 Genera, referred to by Beck (as " S. g.") are the same species. 



Beck defined his minor only by a queried reference to Chemnitz's 

 figures of a West Indian species, really entirely different. 



Distribution. 

 The recorded distribution of Planorbis bicarinatus is shown with 

 approximate exactness upon the accompanying map (pi. III). These 

 data are primarily based upon the collection of the Philadelphia 

 Academy, the complete list of which has been kindly furnished by 

 Dr. Pilsbry. To these have been added such additional information 

 as was afforded by my own collection. The localities thus vouched 

 for are indicated on the map by the black dots. These data have 

 been supplemented by such specific localities as a careful search of 

 the literature at my command afforded. These citations are repre- 

 sented by the outlined dots. Duplicate citations and those giving 

 simply the " State " have been omitted. A detailed list of all locali- 

 ties and the authorities for the same is given below. The map does 



