THE NAUTILUS. 7 
(Terr. Moll., U.S.) the dismemberment of the genus so much de- 
manded by the number of its species, founding the distinction on 
the shell alone.” 
It was as if the court had made up its mind beforehand, but had 
waited for the evidence to establish the decision, and when the evi- 
dence did not support it, the decree was rendered just as the court 
had intended all along. Many of these so-called genera of Helix 
have no value at all, and others so little as to be almost worthless 
for purposes of classification. Our well-known Mesodon runs into 
Triodopsis, and Arionta and Aglaia cannot always be separated. 
Tryon at one time placed Helix devius, Gould, in the genus Mesodon, 
and at another time he, as well as Mr. W.G. Binney, called it a 
Triodopsis. Tryon put Arionta townsendiana, Lea, in the genus 
Mesodon, and Mr. Binney regards Aglaia hillebrandi, Newe., as a 
varietal form of Arionta mormonum. And I might give such illus- 
trations to the end of the chapter, all of which go to show that even 
among the savants these so-called genera are well nigh valueless. 
But let us suppose that in any of the larger genera there is a chain 
of species varying from the type to those which are very unlike it ; 
that the variation is very gradual throughout the species. I cannot 
see that dividing such a genus into a dozen, a hundred, or a thousand 
genera is going to help the matter or give us any clearer insight into 
the relationship of the species. I think that the classification should 
be founded on nature, or in other words, that nature should do the 
classifying, and that our efforts should be directed to deciphering the 
Old Dame’s work. And if a distinction does not exist between cer- 
tain so-called species and genera, it is useless to put it there, as it 
will simply require that somebody in the future, when the truth is 
reached, will have to throw it out. 
The genus Unio, with its thousand species and endless variations, 
has been divided into a number of sub-genera by the genus makers ; 
but a Unio is a Unio for all that, and the merest novice in conchol- 
ogy would recognize it as such in a moment; while probably not 
one conchologist in a hundred could tell a Bariosta, Raf., from a 
Hyridella, Swains. Dr. Isaac Lea showed his great knowledge of 
this subject when he grouped them into mere divisions founded on 
form and sculpture. 
I think the time has come when a healthful reaction from this 
fever of creating genera and species should set in. Such work simply 
renders the science of conchology contemptible, and it is a veritable 
