THE NAUTILUS. 89 



In the upper reaches we have lo fluviatilis, 100 miles lower 

 down we have I. spinosa, I. turrita, and I. brevis. I have collected 

 many thousands of these lo's : spinosa is the most abundant form ; 

 then, after picking out a few turrita and brevis there are always a 

 large proportion that might fit one place as well as another ; there- 

 fore I would call them all spinosa, more or less developed by local 

 causes. Pleurocera sycamorense in one stream becomes P. estabrookii 

 in another, and P. unicale in a tliird. Goniobasis sulcosa in a brook, 

 becomes G. arachnoidea in a creek. Pleurocera parvum and P. 

 Lyoni in a creek in the mountains, become P. fastigiatum in large 

 streams. Dr. Lewis regarded Goniobasis livescens and G. niagarensis 

 the same, and I don't see Avhy Pleurocera curtum and P. conicum 

 should need different names ; and when it comes to the Strephobasis 

 I don't want to name them." Such is the opinion of one who has 

 spent many years of her life in exhaustive research and study among 

 the jNIoUuscs of Tennessee. And when a like thorough search and 

 comparison of all the species of North America has been made I pre- 

 dict that there will be a wholesale addition to the list of our syn- 

 onyms. No doubt in a number of the cases which Miss Law cites 

 the difference between selected specimens was great enough to 

 warrant separating them and giving them names, but the trouble 

 was that intermediate forms of ever}"- degree were found, which com- 

 pletely connected them ; and as in so many other cases this variation 

 was produced by circumstances. 



Now species founded on trivial characters, or those which in- 

 sensibly merge into others cannot stand. I fully agree with my 

 friend Dr. Singley of Giddings, Texas, who says that he wants species 

 which he " can separate from others without the aid of a powerful 

 magnifier and a vivid iraagiuation." 



A careful and earnest student from Kansas writes as follows : '' I 

 have lately collected a large number of Planorbis trivolvis from the 

 rivers and creeks in this vicinity, and I find it a most interesting 

 shell. I can take Binney's Land and Fresh-water shells of North 

 America and a box of these and duplicate a half dozen species figured 

 and described in it." And I believe the same will be found to be 

 true of our Succiueas which need a thorough pruning down in the 

 matter of names. 



And what is a variety ? If species, as they are now recognized 

 among conchologists, hopelessly run together, where shall the varieties 

 appear? What is the difference between a variety and a species, is 



