218 
FOURTEENTH REPORT. 
along the shores and the interior is little known. As our knowledge in- 
creases the supposed differences grow less. But it is not to be ex- 
pected that all differences will eventually disappear. For the region 
north of Saginaw Bay, Beal 3 gives northern plants found on the 
east (Harrisville) and not on the west side (near Frankfort) and cer- 
tain Southern plants found on the west not found on the east side. 
Practically all in both lists are found in the interior, south of the lati- 
tude of Saginaw Bay. Other species named later give additional evi- 
dence tending to diminish the supposed differences. 
This indicates that when particular species are considered, disregard- 
ing their frequency, the differences between the interior and the coastal 
regions are not so great as they are generally thought to be. The limits 
of distribution northward and southward of particular species are not 
sharply defined. Particularly is this true in a region of varied soil 
and surface features. Until much more detailed study is made of other 
areas in the interior it is impossible to state to what extent the vegeta- 
tion and animal life of the interior differ from that of the coast at a 
given latitude. The latitude just south of Saginaw Bay and Alma 
have practically the same average temperature. Cooper's 4 temperature 
records for the vicinity of Bay City, Saginaw, and Saginaw Bay indi- 
cates that there are local differences which appear to be chiefly confined 
to points near the shore. A comparison in the points farther inland 
shows very little influence so far as averages indicate. This is further 
borne out by the fact that in the fauna and flora essentially the same 
species are found. Such differences as exist are yet to be made out. 
Undoubtedly other factors play a very important part, and at times 
they are the deciding factors. Perhaps the most important are; adapta- 
tions and opportunities for distribution, physiographic and edaphic 
conditions and competition and association. Coon’s (See 1 loc cit) has 
shown that these are important factors in the habitats in the sand 
dune region on the south shore of Saginaw Bay, and Livingston 5 has 
found similar relations between habitat and vegetation to exist in Ros- 
common and Crawford counties and also in Kent county. This will be 
seen to be true for habitats in the central part of the State if the Alma 
area is at all representative. 
It is thus seen that in both the coastal regions and in the interior, 
the differences between local habitats are greater than the climatic 
differences between the respective regions. If this be true, the biota 
of the interior and the border areas would differ from each other 
with the relative extent of the various types of habitats. 
The Alma Area, 6 which is the north half of Gratiot county, includes 
the geographical center of the lower peninsula of Michigan, and the 
physical features and climate may be regarded as typical of the central 
portion of the State. It must be remembered however that local condi- 
tions vary somewhat in different localities. The area therefore is im- 
portant from the standpoint of distribution. In this Soil Survey 5 a 
brief description of the area is given and is sufficient for the present. 
3 B e al w .T Michigan Flora, Fifth Ann. Kept. Mich. Acad. Sci., 1903, p 20. 
■•Cooper W F. Geology of Bay County, Mich. Geol. Survey, 1905, pp. 356-358. 
^Livingston B E. Relation of Soils to Natural Vegetation in Roscommon and Crawford Counties, 
Michigan. Ann. Rept. Mich. Geol. Survey, 1903, 9-30. The Distribution of the Upland Plant Socie- 
ties of Kent County, Michigan, Bot. Gaz., 35; 36-55. Map. 
6 H ea rn W Edward and Griffin, A. M. Soil Survey of the Alma Area, Mich. U. S. Dept. Agri. 
Bureau of Soils. Advance sheets, Field operations, 1904. 
