The only known localities for Vertigo morse? Sterki, 
Kent county, Michigan, and northwestern Ohio, may be men- 
tioned in the same connection. 
It would be a matter of great interest if the range of 
these species could be accurately ascertained and compared 
with the data from which the dividing line between the 
Transition and Upper Austral Zones has been established. 
It is possible that definite knowledge on this subject might be 
of value in determining the actual boundaries of these zones 
in the state. 
There are some facts shown by the returns which are of 
interest in regard to the distribution of individual species. 
There are nine species, which thus far have been reported 
from a single locality, viz: 
Vallonia costata (Miill.)..........Shiawassee county. 
Polygyra mitchelliana (Lea)..... Macomb _ 
Pupa muscorum (1,) ..... a .,.-Kent es 
Verso nierse, Sterki.:.... Hye.) |S a 
‘ bollesiana Mse...... Ev  CHaAnlevOLs ae 
me tridentata Wolf..........Washtenaw ‘ 
Grastrodonta intertexta (Binn.)...Sanilac . he 
¥ demussa (Binn.)...... Kent es 
Pyramidula asteriscus (Mse.)....Charlevoix oe 
The carinated form of Conulus fulvus, the var. mortonit 
(Jeffr.) has been found only at Kast Saginaw where, it is 
interesting to note, it was associated with the typical .Stob7- 
lops labyrinthica (Say), also a carinated form. 
The albino form of Pyrvamidula solitaria (Say) has been 
reported only from Kent county. And the corresponding 
form of P. strzatel/a (Anth.) solely from Mackinac Island. 
The apparent absence of Polygyra exoleta (Binn.) from 
the western half of the state is very peculiar. ‘This is one of 
our largest species, not likely to be overlooked by even a care- 
less collector, and it is usually found wherever its near rela- 
tive P. albolabris (Say) occurs, although in Michigan, at 
least, it is not commonly as abundant in individuals. Yet it 
has not been reported from any locality west of the principal 
meridian in the lower peninsula, although it has been found 
as far north as St. Mary’s river in the upper peninsula, while 
its associated species is found everywhere. 
The failure to find the unicolored form of the common 
Polygyra multilineata (Say) in the eastern part of the state is 
also quite curious. 
The apparent restriction of the imperforate form of Po/y- 
gyvra monodon (Rack.) to the southern part of the state, 
9 
