Notice of Ehrenberg’ 
3. The whole number of 
amounts to six hundred and 
roscopic forms included in this review 
of which four hundred and fifty are 
Polygastrica, six Rotatoria, | fragments of plants, (chiefly Phytoli- 
tharia,) fifty six Polythalamia, and two other bodies 
4. All of these six hundred and three minute Lente organisms 
are included in one hundged and three genera, of which twenty five, 
or almost one fourth, are new, but seventy nine, or about three fourths, 
were already known and established. Of these one hundred and three 
genera, sixty four (including six which are peculiar) belong to the four 
rer hundred and fifty Polygastrica. The six Rotatoria belong to five known 
genera. The small forms, consisting of parts or fraginents of organic 
bodies, are assembled in eleven genera. The Polythalamia belong to 
twenty genera, of which five are new and fifteen already known. 
Of the four hundred and fifty species of Polygastrica, two hundred 
and fifty nine, or thirty four more than one half, were hitherto unknown, 
and about one third are peculiar to America, but two thirds are Euro- 
pean. Many of the forms here first named have wie been found 
in Europe. 
In America as in Europe, the genera richest in forms ate, Eunotia 
with forty six species, Navicula and Pinnularia each with forty five 
species. Then follow in the order of the number of species, the genera 
Gomphonema twenty one, Cocconeis nineteen, Stauroneis eighteen, 
Fragillaria, Surirella, seventeen. 
It is remarkable that all the genera distinguished as peculiar, have 
presented but few and generally single species 
5. Drawings of three hundred and twenty "Ave American invisible 
organisms are given, and three hundred and ten are first introduced 
into the systematic list by short characteristics 
6. These examinations have led to the eavibliilinient and systematic 
Teview of two hitherto unconsidered great groups or families of mi- 
croscopic bodies, which indeed are not independent organisms, but have 
nevertheless the same worth for geological researches, viz. the uncrys- 
talline siliceous bodies arranged under the family name Phytolitharia,* 
and the organized calcareous fragments referred to the family Zooli- 
tharia. Liki all other species of fossils, these are suited to form a 
good basis for geological conclusions. 
7. The eleven species whose names are given in the following - 
distinguish themselves from all others by their distribution, and co 
Sequently their influence. They may be considered as coner rs 
(Weltbirger,) as they are found agreeing in character from the most 
* Various Phytolitharia are represented in this Journal, Vol. xuu 5, figs. 
os to 35, and in Hitchcock's Report on the Geology o FMamachoat, Om Il, PL. 
fig, 29, 
