Sketch of the Infusoria of the family Bacillaria. 327 
confervoid, resulting from perfect division of the carapace, and 
imperfect division of the mantle. 
In this genus, corpuscles which cannot be distinguished from 
those of Navicula are assembled together in vast numbers, in flex- 
ible membranous tubes, within which they may often be seen to 
move freely. ‘They doubtless often leave these tubes, and then 
appear like species of Navicula. 
Ihave noticed several American species, but I am unable to 
decide whether they are identical with any hitherto described, 
as I have had very little opportunity to study our species ina 
living state and have no foreign specimens or figures to compare 
them with. I shall therefore content myself with merely giving 
the forms of the frustules found in each species, and such addi- 
tional particulars as seem most interesting. 
1. Naunema (Pl. 3, fig. 14.) The figure represents cor- 
puscles from a branching species found on the shores of Staten Island, 
N.Y. The tubes are whitish, containing long rows of corpuscles, 
strung end to end, each of which contains two round globules looking 
like air-bubbles. No trace of striz. 
nema . (Pl. 3, fig. 15.) This figure shows the form 
of saipaaelaa which filled short robust unbranched filaments, which 
were exceedingly lubricous. Bunches of filaments about half an inch 
in length, were found in great abundance on Zostera, Sc. at Stoning- 
ton, Conn. 
3. Naunema (Pl. 3, fig. 16.) This figure shows the out- 
line of dried espiuias ‘froin a specimen obtained at Stonington, Conn., 
where it is very common. Its filaments are branched and form larger 
and longer — = the preceding, with which it occurs. 
4, Nawnema (Pl. 3, fig. 17.) ‘This is from specimens found 
in immense quantities in the Hudson River, at West Point. The masses 
have not the green color of the two preceding species, but present a 
rich brown color. The frustules are in all respects like those of Navi- 
cula, and I have often seen them move spontaneously in their tubes, 
some going one way and others another. 
~ In Pl. 3, fig. 17, a, is shown the outline of much longer frus- 
tules, found in tubes similar to those just mentioned. 
GLOEONEMA. 
- Envelope double, carapace siliceous, mantle tubular, tubes sim- 
ple, often branched, eorpuscles curved resembling Co in 
atube. ae. | 
