302 Sketch of the Infusoria of the family Bacillaria. 
I will now proceed to describe briefly some of the most inter- 
wting American species of Closterium, giving in connection with 
the characters of the European species which appears to 
correspond to our own, as far as I can determine by the brief ac- 
counts, usually unaccompanied by figures, in the works to which 
I have access. 
1. Closterium heats (Fig. 30, Pl. 1.) Semilunar or straight, di 
minishing gradually towards the rounded extremities, internal glands 
scattered, green granules arranged. in several (10) threads, ¢ to 7b line, 
2. Closterium .moniliferum. (Fig. 31, Pl. 1.) Semilunar, never 
straight, smooth, acute, and rounded at the ends, internal glands inthe 
middle of the body arranged ina moniliform manner, green granules i a 
several Tows, of which the three middle ones are most distinct. 
Specimens. agreeing with the characters of each of the above 
species ‘are common in this country. They do not however ap- 
pear to be specifically distinct. They may be easily recognized 
by their smooth, green, crescent-like forms. 
~ 8. Closterium trabecula. (Fig. 32? PL. 1. ) Straight, cylindrical, 
er eT in the middle, smooth, the ends truncate, ice scattered 
or in several series, numerous obscure bands, 3}; to + lin 
Ihave seen no figure of this European species, “hi I never- 
theless venture to refer to it, the fine species represented in figure 
32. This is the largest Closterium which I have seen in the 
United States. It occurs at West Point, at Staten Island, aud | in 
Virginia. 
- Its motions are quite distinct, “the cavities containing moving 
particles very apparent, and what appear to be terminal openings 
may be easily seen. By application of tincture of iodine, and 
then crushing the specimen under the compressor, starch glo- 
bules may easily be detected. In crushing, the globules are of 
ten forced out at the terminal openings, and on relieving the pres- 
sure are drawn back again. No rupture of a membrane at these 
points was perceived. 
4. Closterium digitus. i 33? Pl. 1.) Straight, oval, cylindri- 
cal, four or five times longer than broad, smooth, the ends very 
d, sometimes showing traces of a spontaneous triple division, 
longitudi na bands often denticulate, zo to +, line. 
With this account may be com red fig. 33, Pl. 1, which rep- 
resents a species not uncommon at West Point, and Chih I have 
also seen in Rhode piel, Virginia, and Ouisconsn 
ORS 
