132 
MONOGRAPH OF THE GENUS STROP HI A. 
It is a well known fact that in some genera, or even families, in 
all classes of animals, species are much more close!} 7 allied than in oth- 
ers, and that certain characters are constant in some genera, thus are 
available in defining species, which are inconstant and thus valueless for 
this purpose in others. 
Any naturalist, not narrowed down to a specialty, will acknowl- 
edge the truth of the above made statement, as his attention must be 
constantly called to it in his imvestigations. 
Again, we must acknowledge that groups of animals in which spe- 
cies are not readily defined, require the closest study in order to clearly 
understand just what characters are of value in deciding specific rank. 
The genus Strophia presents one of these very problems, and 
whether from the difficulty of recognizing species, or from some other 
cause, has been strangely neglected, as I have had occasion to remark 
many times, by naturalists on this side of the Atlantic. It is true that 
there is quite an extensive literature upon Strophia in connection with 
Pupa, but very much of this is valueless on account of too great gener- 
alization in describing species. Then again, two, or more, species are 
often included under one name, consequently descriptions become very 
confusing. 
1 may appear to be making a sweeping statement here, but am 
sure that I am correct in this assertion. As proof of this I have only to 
bring forward the fact that in some of the largest collections in the 
country, that have been examined by me, names are applied to compar- 
atively few species, and when applied are often obviously wrong, as the 
same name is, in many cases, appended to more than one species, while 
on the other hand, instances are not wanting where the same species 
has received different names! 
Now I do not pretend that I have done any more than any one 
can do in the study of Strophia, who has modern ideas regarding species 
and the requisite training. But I have given the subject very much 
attention and thought. It is true, that I have much to learn, for there 
is a broad field still before me, but as far as I have been the matter ap- 
pears perfectly clear to me. 
I cannot help feeling that many conchologists, at least in America, 
are unfamiliar with this genus through prehaps having neglected it as 
of not sufficient importance to warrant the application and thought that 
the subject merits. I may say, however, that since the appearance of 
the first number of my monograph, I have met with much kindness, as 
well as encouragement, from many prominent naturalists who have aid- 
ed me in many ways in prosecuting my researches. 
