The Nautilus. 



Vol. III. NOVEMBEB, 1889. No. 



THE VIRGINIA COLONY OF HELIX NEMORALIS. 



BY T. D. A. COCKEFIELL. 



Pei'haps 8ome of your readers, when they see the lonir list l)elow 

 of varieties differing only sliuhtly from one another, will think it a 

 case of much ado about nothing, and wonder where the interest 

 can he in such minute differences of color or banding. 



In these days it ought to be unnecessary to apologise for going 

 into precise detail in scientific matters, but I will venture to point 

 out that the present case is one of quite exceptional interest. 



Here we have an exceedingly variable species, whose varieties 

 have been extensively studied in its native country — Europe, and 

 found to differ greatly according to locality and circumstances. 

 A few of these varieties may be traced to definite causes — most of 

 them appear to occur causelessly, which is another way of saying 

 that the cause is, in these cases, as yet unknown. A highly variable 

 species, then, is introduced into a new continent, where climatic and 

 other conditions differ markedly from those of its native home. 

 It is certain to vary — it varies everywhere — will it not, then, be 

 influenced in its variation by the new environment, and produce, 

 perhaps, new and unheard-of forms ? And if so, shall we not thereby 

 have a valuable clue to the nature of these forms, and the general 

 principles which underly the phenomena of variation in this and 

 perhaps in other species? In the endeavor to answer these ques- 

 tions I shall feel excused, both now and hereafter, if I seem to go 

 into these matters more minutely than is usual with conchological 

 work. Mys3lf, I believe that in the noting of minute differences 



