20 VHE NAUTIHS. 



PHYSA HETEROSTROPHA. 



BY O. A. CRANDALL, SEDALTA, MO, 



Is there such a spet^ies as that described by Say ? If so, what is 

 it? I am led to make this inquiry after a study of this geuus for 

 several years. The first question Avill of course be answered unani- 

 mously in the affirmative, but how many will agree as to the main 

 characteristics of the species? I have examined during the last 

 year many lots labelled P. heterostropha Say, and have not found 

 two lots alike. They include all forms from the cylindrical P. gyrina 

 Say, to the shouldered P. ancillaria Say, and have any number 

 of whorls from three to six. Most of them were labelled by ama- 

 teurs, who have no means of identifying the species except by fol- 

 lowing a rather meagre printed description ; and it can hardly be 

 expected that all should agree. Very few collectors have oppor- 

 tunity to see type specimens, and it is very annoying to have to 

 send every " find " to some noted conchologist for identification. 

 Besides, I find about as much diversity of opinion regarding Physre 

 amongst our professors as amongst amateurs, hence, I write this 

 article for the purpose of procuring a correct description of this 

 species. Say describes the shell as " subovate, having /o»r whorls, 

 the first large, the others terminating rather abruptly in an acute 

 apex ; aperture large, somewhat oval, three-fourths the length of 

 the shell, or rather more." These are the only characteristics given 

 that are not common to many other shells. Binuey, in " Land and 

 Fresh Water Shells of N. A.," part 2, page 84, gives two figures : 

 Fig. 144 from Say's type and Fig. 145 from Say's figure, which are 

 about as near alike as a bean and a pea. Which shall we follow? 

 The description is silent as to the form of the spire whorls and sut- 

 ures, but from the fact that Fig. 144 shows convex whorls and 

 impressed sutures, and from the other fact that Binney, after hav- 

 ing seen the type specimen, placed in its synonymy P. philippn 

 Kuster, P. cylindrica Newcomb, P. fontana Hald. and I'. pHcata 

 De Kay, all of which have somewhat convex whorls and impressed 

 sutures, it is fair to presume that these characters belong to the 

 shell under consideration. 



Add this presumption to the description given by Say, and we 

 have a very fair description of what is generally considered one of 

 onr most common shells, and which ought to be easily identified by 



