128 THE NAUTILUS. 



I am unable to find that any previous collecting has been 

 done either in the Big Snowies or the neighboring ranges, but 

 Mr. Robert Wellington brought me a few specimens of a larger 

 and more typical race of OreoheUx cooperi from near the head of 

 Neil Canyon, on the same side of the range as the present lo- 

 cality, but some miles to the westward. 



It might be added that I have taken Planorbis antrosus, Physa 

 gyrina, and Lymnaea caperata in some abundance in the pools 

 and ditches along the river bottom at Harlowton, Montana. 



I am indebted to Mr. Frank C. Baker for determinations of 

 the Lymnaeidae mentioned in this article : to Mr. E. G. Vanatta 

 for various help in verifying and comparing specimens ; and 

 likewise to Dr. H, A. Pilsbry and Mr. George H. Clapp. 



BEVEBSED OR SINISTBAL SHELLS. 



BY F. A. SAMPSON. 



In Nautilus, vol. ix,, 1895, p. 94, Prof. Wetherby told of 

 three reversed shells which had belonged to him. A P. thy- 

 roides and a P. midtilineata he had given to John G. Anthony 

 for the Cambridge collection, and at that time he had another 

 thyroides in his collection. He did not give the locality of the 

 shells, but as he had formerly lived at Cincinnati, it is probable 

 that the shells were from that neighborhood. He knew of a 

 third thyroides collected near Cincinnati by Mr. Stannage, and 

 of a mitchelliana collected by Prof. F. W. Bryant near the same 

 place. Dr. Lewis had an albolabris in his collection. 



In Nautilus, vol. x, January, 1897, p. 104, C. F. Ancey 

 gave a list of 21 sinistral specimens of shells that were normally 

 dextral. Only two of them were American — Polygyra thyroides 

 from Connecticut, and Campeloma deciswn from New York. 



In the February number of the same volume Pilsbry reported 

 that he had a collection of Campeloina decisum made by W. W. 

 Jefferis, of Philadelphia, collected at Fort Edward on the Hud- 

 son River, New York, examined for sinistral shells, and among 



