1914 ] 
Jackson: Land Vertebrates of Ridgeway Bog 
31 
places would easily account for the absence of the loon {Gavia 
nnmer) . 
The Aquatic Association having gained a foothold, gradually 
deposits were added to the benches and flats, which, coincident 
with the deepening of the drainage system, approached the water 
surface and allowed the invasion of the Sedge Association, the 
Aquatic Association in the meantime encroaching towards the 
center of the lake. This stage of the bog development is illustrated 
today in such lakes as Jennie Webber and the second of the Moen 
chain in Oneida County, Wisconsin. The biota of Jennie Webber 
Lake has not been sufficiently studied, but that of the second Moen 
Lake^^ is very similar to that of the Aquatic-Sedge Associations 
of Ridgeway Bog; Scirpus lacustris and Nymphaea odorata, how- 
ever, were still present in the Aquatic Association, but sphagnum 
and Potentilla palustris were not found; Gavia mimer occurs only as 
a casual visitor and is not Imown to breed; Circus hudsonius and 
Telmatodytes p. iliacus were not seen, while the bittern (Botaurus 
lentiginosus) was not uncommon, and the osprey {Pandion haliaetus 
carolinensis) was seen on two occasions fishing from the lake. 
The Sedge Association is a narrow zone and was evidently very 
soon invaded by the Cassandra Association. At this stage three 
vertebrates, Thamnophis, Microtus, and Blarina, were probably 
found in continuous distribution from the Hillside Association 
to the Sedge Association; they are found today in various locali- 
ties in the immediate region in similar adjoining habitats; but 
with the invasion of the Cassandra Association by the Tamarack- 
Spruce Association, and this later by the Cedar-Balsam-Hemlock 
Association, an ecological barrier was created which separated 
their habitats apparently as effectively as would a geographical 
barrier. 
Theoretically the Aquatic Association will advance, followed in 
turn by the Sedge, Cassandra, Tamarack-Spruce, and Cedar- 
Balsam-Hemlock Associations until the whole original bog area 
will be converted into the mesophytic forest of the Cedar-Balsam- 
Hemlock Association. Ecological processes such as these, viewed 
from the human standpoint, are slow and long-drawn out; viewed 
from the geological standpoint, however, they are rapid and fast- 
following. Ecological evidence has been sufficient from the bo- 
12 Observations on Moen Lake were made August 11-13, 1906. 
