MIDLAND NATURALIST. ET 
uei. from one point and in the third order the radiating needles 
e six. Now comes the all important question in this study. 
Where shall we place the Fresh Water Sponges? If we follow 
Hornell’s classification the question is simple. In all Fresh Water 
Sponges the spicules are siliceous and of the monaxial type, and so 
they must belong to the class of Silicispongiae and to the order of 
Monaxonida. 
. Vosmaer places the Fresh Water Sponges into the third order 
of the Non-Calcarea which he calls Cornacuspongiae; and he gives 
the following diagnosis: ‘‘Skelet besteht entweder aus, vorwiegend, 
monaxilen Spicula, welche durch mehr oder weniger spongin zusam- 
mengekittet sind, oder nur aus spongin mit oder ohne Vestárkung 
von Fremdkorpern. Leben in See,—brackischem und Siiss-wasser 
meist nicht sehr tief." Translated this means that in the Corna- 
cuspongiae ‘‘the skeleton consists principally of monaxial spicules . 
which are cemented together more or less by spongin, or the skeleton 
consists merely of spongin with or without strenghtening of foreign 
bodies. They are found in salt water—brackish water—or in 
fresh water and not at great depths." Thus we see that Vosmaer 
places the Fresh- Water Sponges in the same group as the ordinary 
commercial sponges which are all marine; he however 
separates them from each other by creating two sab- orders viz.: the 
Halichondrina, in which the fresh-water sponges are found fcrmin 
the second family called Spongillidae, and the stain which include 
the commercial sponges as Family two, viz.: Spongi 
I need scarcely say here that the ae po will 
find no difficulty whatever in identifying the Fresh Water Sponges. 
Fresh Water Sponges properly so called are only found, as a matter 
of fact, in fresh water, all other sponges are found in the sea, and so 
whenever a sponge grows in fresh water one need have no fear of 
making a mistake as to identity. Let this be the guide for the be- 
ginner and after he has found a few Fresh - Water Sponges and 
studied them with the low power or high power of the compound 
microscope he will gain the knowledge to distinguish them from 
marine forms. There are difficulties in the study. There are so 
many things growing in fresh water, but one should not be dis- 
couraged, for the matter is not as difficult as it seems. First one 
must get overthe idea that everything green in the water must be ` 
a plant —an alga or some moss. The former one will at once reject 
when one sees that it consists of simple or branching green threads 
and the latter has small green leaves which even one-inch hand lens 
will make plain. All one needs in the field is a hand lens of one inch 
