162 Address to the Lincolnshive Naturalists’ Union. 
This species is Limnea glabva, one whose non-occurrence, or 
rather our want of knowledge of its occurrence, has long 
puzzled our conchologists. Till this year the only record has 
been of examples found on the south side of Lincoln city by 
Rev. Canon W. W. Fowler, the coleopterist. This locality was 
almost immediately destroyed, so the species had to be regarded 
as extinct. The distribution of the species outside our county 
added to the puzzle, for it has not a few localities in neighbouring 
parts of Yorkshire, on old common lands, of which my late 
friend, Mr. William Nelson, regarded it as a characteristic, 
and therefore, with the gradual disappearance of the old 
commons, a dying-out species. 
Another interesting circumstance in regard to the life history 
of Limnea glabra is the fact that it is one of a trio of molluscan 
species which associate together in their habitats in pretty much 
the same manner as such diverse animals as zebras and 
various species of antelopes do on African plains. The other 
two species are Planorbis spivorbis and A plexa hypnorum, which are 
both common in many Lincolnshire localities. 
The discovery of Limnea glabra this year was made at our 
Scunthorpe meeting and—as was also the case with the Lincoln 
record—by a coleopterist. 
It was our friend Dr. Wallace, who, sweeping a pond 
for water-beetles, found a few small shells, which, being 
submitted to the conchologists, were at once pronounced to be 
this long sought for species. 
Circumstances prevented the immediate following up of this 
discovery, but a month later Mr. J. F. Musham and I enlisted 
the aid of Mr. Alexander M. Cobban, of Scunthorpe, for the 
purpose of confirming the record and of making as exhaustive 
a study as we could of its environment and surroundings, and 
the conditions under which it flourished. Thanks to Mr.Cobban’s 
local topographical knowledge, the place was found without 
much difficulty, and the shell was found to be an abundant one 
in various stages of growth, and associated with Planorbis spirorbis 
var. votundata, and Pisidium pusillum, all commonly, and one 
solitary example of Limna@a peregra. Water insects were in 
