3 l6 
The Ohio Naturalist. 
[Vol. VIII, No. 6, 
Station at Sandusky, about three miles distant across the Bay 
was 79 degrees, Fahr. (At 1 inch above the surface of the soil 
the air was 118 degrees; at 6 inches, 89; at 12 inches 84,—ther¬ 
mometer properly shaded.) 
Thus far the vegetational structure in the succession under 
consideration has been comparatively uniform over the entire 
Sand Plain wherever the latter may be situated on the peninsula, 
but the Artemisia-Panicum Formation may be invaded and 
eventually succeeded by a formation having distinctly northern 
phytogeographical relationships, or, on the other hand, the 
succeeding formation may be one of more southern affinities. 
Fig. 7. Small area of Sand Plain enclosed by Quercus velutina and Q 
imbricaria, Celtis occidentalis. Note communities of Opuntia humifusa 
with scattering Artemisia, Panicum virgatum , P. scribnerianum and 
Verbascum thapsus. 
In the work on Presque Isle the writer found a considerable differ¬ 
ence in both the habitat and in the corresponding vegetation in 
different portions of the Sand Plain such that two formational 
series could be distinguished as early in the succession as the 
Drift Beach. On Cedar Point, however, there are no such evi¬ 
dent distinctions early in the succession but the critical period 
appears to be in the sand plain stage. 
Accordingly, the succeeding vegetational structures with a 
more southern phytogeographical relationship will first be taken 
up, after which the structures of northern affinities will be dis- 
