PYRGULOPSIS SCALARIFORMIS, (Woll) Call and Pilsbry. 



(Plate XIII.) 



By B. SHIMEK. 



In the American J\'aturalht for January, iS86, Mr. H. A. 

 Pilsbry reported the discovery of a form of Pyrgiila scalari- 

 formis. Wolf, near Rock Island, 111., for which the varietal 

 name mississippieyisis was proposed. 



In a paper read before the Davenport Academy of Natural 

 Sciences, 1 February 20th, 1S86, IMessrs. Call and Pilsbry 

 describe the same form under the specific name ■inississip- 

 fiensis^ and refer it to the new genus Pyrgtilo-psis^ which is 

 therein proposed, together with typical P. scalar if or mis^ Wolf. 



In both papers this mollusk is treated as modern, although 

 the statement is made in the latter that "many dead speci- 

 mens have been taken, but as yet, no living ones." Acting 

 under this impression, the writer, some two years ago, visited 

 the locality in which Mr. Pilsbry made his discovery, with the 

 determination to find living specimens of this interesting little 

 mollusk, if possible. 



Numerous bleached specimens were found along the east 

 arm of Rock River, on the sand-bar (f/. Fig. i), but the 

 dredge failed to bring up any living examples above this 

 point. An examination of the bank between the points a and 

 b (Fig. i) however revealed a number of interesting facts, 

 not the least of these being the presence of great numbers of 



I Vide, Proc. D. A. N. S.,VoI. V. 



