I' 



The Nautilus. 



Vol. XXI. OCTOBER, 1907. No. 6. 



NOTES ON PLANOEBIS.— I. 



BY BRYANT WALKER. 



Plaxorbis mlltivolvis Case. Plate VIII. 



This species was described by William Case, of Cleveland, 0., in 

 1847 (Am. Jour. Sc. [2], III, p. 101), from specimens collected by 

 Captain B. A. Stannard, '• in the northern part of Michigan." 

 Most, if not all, of these specimens, apparently, were given by Case 

 to Dr. Gould, who distributed a few and deposited the balance in the 

 collection of the Boston Society of Natural History. Examples 

 were sent to the Cuming Collection (now in the British Museum), 

 from wliich the species was well illustrated in the Conchologia 

 Iconica by Sowerby, whose figures were copied in the Conchylien 

 Cabinet. 



A single specimen found its way into the Jay Collection now in 

 the American Museum of Natural History, and another was given 

 to the Smithsonian Institution. Subsequently Dr. Gould gave sev- 

 eral specimens to Dr. W. H. Dall, which are now in the National 

 Museum. So far as I have been able to ascertain, the original lot is 

 not represented in any other collections. 



From that time until 1906 nothing further has been known of the 

 species. In 1888 (J. of C, V, p. 330), on the authority of the late 

 Geo. W. Tryon, Jr., I announced the re-discovery of the long-lost 

 species in Marl Lake, Roscommon County, Mich. But a subse- 

 quent comparison with genuine specimens showed that the identifi- 

 cation was erroneous. The Marl Lake shells are probably P. 



