Certain Protozoa and Other Invertebrates. 239 
it was common during the summer, but concealed by its green sub- 
stratum. June 22 (1906) it was plentiful on the weeds in Lost Lake. 
In a note of June 26, concerning this species, occurs the remark, 
“This is a larger sort; there are also other smaller isolated ones pres- 
ent.” On July 25, and previously, it was common in both lakes in 
weedy, stagnant places, forming a white halo along stems, not in balls. 
In addition to these there are minute free Vorticella-like organisms 
attached to the parasitic copepods on the gills of fishes, and on August 
28 (1908) a number of minute clear Vorticellas were found on the body 
of a Cyclops. A species of Vorticella was abundant July 31 (1906) on 
Anabena in plankton scum. Small Vorticellas are found in myriads on 
objects in Hawk’s marsh. They can be found there more abundantly 
than anywhere else about the lake. 
12. Epistylis sp. 
A species of Epistylis, probably plicatilis Ehrenberg, was observed 
forming a dense growth on the shells of a small Planorbis, March 25 
(1901) near Chadwick’s pier. 
The copepods of the same region at that time presented a very fuzzy 
appearance, and upon examination were found to be thickly overgrown 
with the same or a similar protozoan. 
13. Opercularia ivritabilis Hempel 
Abundant during the summer and autumn of 1906 upon the lower 
surface of the shell (plastron) and also on the skin of various turtles, 
especially the painted and snapping turtles, making a close, short, brown 
fuzzy growth. The turtles were botanic gardens above and zoological 
gardens below. The organisms seemed to do them no injury, and were 
gotten rid of when the turtles shed their scutes. It sometimes forms a 
halo about the heads of smali turtles, in which case it was at first mis- 
taken for Saprolegnia. It is usually the head of the Musk Turtle that 
is affected. In this case it appears to do no harm, as the turtles are 
quite lively. 
Something very like this, probably the same thing, was observed 
abundantly (August 6, 1907), on the shoulders of a dragonfly larva. 
14. Vaginicola leptosoma Stokes 
A species of Vaginicola, perhaps leptosoma, was rather common 
along the shore of the lake by Overmyer’s hill, attached to alge, Octo- 
ber 28 (1906). There were at least six examples on one small bunch 
of algez. The sheath was brownish and transparent. When jarred, the 
animal retracted into the sheath, usually doubling up somewhat into a 
sigmoid curve. 
15. Tokophrya quadripartita (Claparéde & Lachmann) Butschli 
Common, intermixed with Opercularia irritabilis, on the ventral 
seutes of a Musk Turtle, September 12 (1906). It was also found to 
some extent on the back. 
