is the only locality reported for either of these species south 
of the line of Wexford and Iosco counties. The remaining 
five boreal species have thus far been found only in the Grand 
Traverse region and along the St. Mary’s river in the upper 
peninsula. 
The remaining forty nine species comprised our fauna 
belong to the Interior Region of Binney, which corresponds 
substantially with Transition and Upper Austral Life Zones 
as established by C. Hart Merriam. Of these, twenty one 
species have a general distribution as far north, at least, as 
the eastern extremity of the upper peninsula. One, Polygyra 
say’ (Binn.), is apparently restricted to the northern part of 
the lower peninsula, but on the east coast comes down as far 
south as Tuscola and Huron counties. While the remaining 
twenty seven species have not, as yet, been reported from 
north of the Saginaw-Grand valley, except Polygyra leaii 
(Wd.), and Gastrodonta intertexta (Binn.), which range north- 
easterly into the ‘‘Thumb” (Huron, Tuscola and Sanilac 
counties). Ihave been unable to satisfactorily correlate the 
apparent distribution of these various groups with the life 
zones established by Dr. Merriam. Whether it is because the 
data at hand are insufficient, or because the mollusca are not 
as susceptible as other forms of life to the peculiar local con- 
ditions upon which they are based, or because the data from 
which the lines of these zones across the state have been 
established are insufficient and therefore possibly inaccurate, 
I do not know. They are, I understand, so far as Michigan 
is concerned, more or less theoretical and, I am told, do not 
coincide with the views of some of our local observers. 
According to Merriam, the upper peninsula and the 
northern part of the lower peninsula lying east of the Grand 
Traverse region, and north of Tosco county, belong to the 
Boreal Zone. 
The Lake Michigan shore as far north as the mouth of 
Grand Traverse Bay and the entire southern part of the state, 
lying south of (approximately) the north line of Jackson, 
Washtenaw and Wayne counties are included in the Upper 
Austral Zone. 
While the remainder of the state, including the Grand 
Traverse region, form part of the Transition Zone. 
Of the five purely boreal species belonging to our fauna, 
all are found at Charlevoix and Petoskey, which are in the 
Grand Traverse extension of the Transition Zone. While 
Polygyra sayti (Binn.), which in Michigan is quite as char- 
acteristic a northern form, is found from Charlevoix on the 
west coast to Huron and Tuscola counties east of Saginaw 
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