veniences for comparative study, will communicate these semi-fossil 
species to those who have, we can, within a few years, have a new and 
very interesting chapter added to North American conchological liter- 
ature, and I invite the attention of my brother workers in this field 
to this suggestion in the hope that some of them may address them- 
selves to the labor systematically; and I shall always be most happy to 
receive any suggestions, to reply to any questions, and to examine any 
specimens so collected. 
I also call especial attention to another class of shells which I hope 
to see industriously collected. Ireferto the small Pupas, Helices and 
Vertigos, and to the Succineas, Limneas and Physas, These shells are 
unfortunately neglected in comparison to their more fortunate relations. 
of larger size and plainer specific distinction. 
They are neglected because it is not always easy to determine the 
species, and thus because they are “ difficult.” But I have elsewhere 
endeavored to show the value of all these circumpolar forms, and sub- 
sequent studies, and the accession of large European additions to my 
collections, have rendered it certain that these very shells will afford us 
some of the most useful and interesting that can possibly be acquired. 
Limneus and Physas. should be collected late in the fall, or 
very early in the spring, or at any time when possible during open 
winter weather. They will, at such seasons, be found to have the hp 
hard and perfect. The animals should be carefully extracted, and the 
shells so packed as to suffer no breaking in transit. A few specimens 
of each species, from every locality, should always be put into whisky, 
or alcohol somewhat diluted with water, say one half alcohol. The 
minute Helices can be collected to better advantage in open winter 
weather than at any other time, since they are collected together in 
groups for hibernation. Collectors in the west, northwest in the 
extreme north, and in every region where these shells form the bulk 
of the conchological fauna, should especially work up these genera 
with great industry. 
Let us remember that the mont important object is not the mere 
fact of amassing a collection, but to have it as perfect an epitome of 
the groups collected as may be; an object only to be accomplished by 
persistent endeavor, and that which is intelligently directed. 
Notes on American Land Shells. 300 | 
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