ed, the free surface
Protozoa were not studied, nor was the dredge called into play. Both
of these means of collecting promise excellent results, and at some
future time I hope to take advantage of them.

My observations cover a period of two months, from the 1st of July
to the 1st of September. During that time I was able to study and
describe 72 species representing 55 genera, all from the limited
space mentioned above. In addition to these there are a few genera
and species upon which I have insufficient notes, and these I shall
reserve until opportunity comes to study them further.

I take this opportunity to express my thanks to Dr. Hugh M. Smith
for many favors shown me while at Woods Hole.

In dealing with these marine forms from the systematic standpoint,
two courses are open to the investigator. He may make numerous new
species based upon minor differences in structure, or he may extend
previous descriptions until they are elastic enough to cover the
variations. The great majority of marine protozoa have been described
from European waters, and the descriptions are usually not elastic
enough to embrace the forms found at Woods Hole. I have chosen,
however, to hold to the conservative plan of systematic work, and to
make as few new species as possible, extending the older descriptions
to include the new forms.

The different classes of Protozoa, and orders within the classes,
are distributed more or less in zones. Thus the Infusoria, including
the Ciliata and the Suctoria, are usually littoral in their habitat,
living upon the shore-dwelling, or attached, water plants and upon
the animals frequenting them. It is to be expected, therefore,
that in forms here considered there should be a preponderance of
Infusoria. Flagellated forms are also found in similar localities,
but on the Surface of the sea as well; hence the number described
in these pages is probably only a small proportion of the total
number of Mastigophora in this region. The Sarcodina, including the
Foraminifera and the Radiolaria, are typically deep-sea forms and
would not be represented by many types in the restricted locality
examined at Woods Hole. Two species, _Gromia lagenoides_ and
_Truncatulina lobatula_, alone represent the great order of
Foraminifera, while the still larger group of Radiolaria is not
represented at all.

The Protozoa described are distributed among the different orders as
follows:*

Class SARCODINA.
Subclass