96 
Ohio Naturalist. 
[Vol. 1, No. 6- 
SPONGES AND BRYOZOANS OF SANDUSKY BAY. 
F. L. Landacre. 
The two small groups of fresh water sponges and Bryozoa re- 
ceived some attention at the Lake laboratory during the summer 
of 1900 
All our fresh water sponges belong to one family, the Spongillidae, 
which has about seven genera. They differ from the marine sponges 
in two particulars. They form skeletons of silicon only, while 
marine sponges may form silicious or limy or spongin skeletons. 
The spongin skeleton is the one that gives the bath sponge its value- 
They also form winter buds or statoblasts which carry the 
sponge over the winter and reproduce it again in the spring. This 
peculiar process Avas probably acquired on account of the changes in 
temperature and in amount of moisture to which animals living in 
fresh water streams are subjected. The sponge dies in the fall of 
the year and its skeleton of silicious spines or spicules can be found 
with no protoplasm. The character of the spines in the body of the 
sponge and those surrounding the statoblast differ greatly, and those 
around the statoblast are the main reliance in identifying sponges. 
So that if a statoblast is found the sponge from which it came can 
be determined, and on the other hand it is frequently very difficult 
to determine the species of a sponge if it has not yet formed its stato- 
blast. The statoblast is a globular or disc-shaped, nitroginous cell 
with a chimney-like opening where the protoplasm escapes in the 
spring. The adult sponge is non-sexual but the statoblasts give rise 
to ova and spermatozoa which unite and produce a new sponge. The 
statoblast is considered as the sexual generation. 
Three species belonging to one of the seven genera were posi- 
tively identified. 
Spongilla fragi/is, Leidy, a very common form was found on sub- 
merged rocks on the south side of the bay near the city in great 
abundance. Its yellow statoblasts are numerous and placed in 
layers near the base of the sponge on the rock to which it is 
attached. 
Another species Spongilla cinerea, Carter, was found on floating 
timber. It is ashen gray in color. 
A third species Spongilla aspinosa , Potts, was found in Black 
Channel and near the city on submerged rocks. Its color is green. 
Other species were found but not definitely determined. 
The fresh water Polyozoa comprise a small group of animals 
resembling the sponges in the process of statoblast formation, but 
otherwise totally different. Their real relationship is not definitely- 
