388 Wisconsin Academy of Sciences^ Arts^ and Letters. 
Najas flexilis Rost. & Schmidt. 
Vallisneria spiralis L. 
Ceratophyllum demersum L. 
Myriophyllum verticillatum L. 
Chara crispa L. 
3. Swamp, pond and river species which may be found lo¬ 
cally, in places where the lake tends to swamp, and also oppo¬ 
site the mouth of rivers and creeks. Largely emersed species. 
Lemna minor L. 
Lemna trisulca L. 
Scirpus lacustris L. 
Castalia odorata Wood & Wood. 
Utricularia vulgaris, var. americana Gray. 
Typha latifolia L. 
Radicula nasturtium-aquaticum L. 
Ranunculus delphinifolius Torr. 
Nymphaea advena Soland. 
Philotria canadensis Britt. 
Wolffiia Columbiana. Karst. 
Zizania aquatica L. 
The Macrofauna 
I. INVERTEBRATE PHYLA (eXCL. ARRTHROPODA) 
1. Porifera. 
Spongilla fragilis Leidy. 
Only the encrusting form of this sponge occurs in the lake, 
on the rocks of Maple Bluff, Governors Island, and Picnic 
Point, and in parts of the Yahara Spillway. 
2. Coelenterata. 
Hydra fusca Linne. 
No numerical data of this species are given. It is ubiquit¬ 
ous in the littoral area of the lake, and locally may be found in 
enormous quantities. A Myriophyllum plant with seven 
branches totalling a length of four meters was found to hold 
over 15,000 specimens. In late fall the'sexual individuals are 
especially abundant. Hydra may hibernate, but in quite re¬ 
duced numbers. Probably the greatest representation of Hy¬ 
dra may be found along the channel of the Yahara River to 
