150 SKETCH OF TfrE INFUSORIA 



Several of tlio jiositions ol" ihcse singular productions are well 

 rcprosontod by Miiller. (See Encyc. Meth., Vers, PI. fig. 16-20.) 

 MiiUcr found his specimens abundant on Ulva latissima ; I found 

 mine pretty common among Enteromorpha, Poli/siphonia, and 

 Potamo^cion, which grow together in brackish water on the flats 

 in the Hudson River, near West Point. 



2. Bacillaria? tahcUaris. (PI. II, fig. .30, a, 6.) Smooth, carapace 

 linear, narrow, swollen in the middle, dividing into quadrangular 

 jilates of variable length, ovary lobcd and yellow, ^\ to ^ of a line, 

 (width of lilament.) Sj-n. Diatoma focculosum, Kutz., Linn. 16.33, 

 PI. 17, fig. G7. Diatoma flocculosum, Greville, in Brit. Flora, volume 

 V, p 40G. 



This species is very common in all parts of the United States 

 which I have visited. It is easily recognized by its zigzag chains, 

 composed of plates (individuals) of various width, which have 

 the middle and two outer edges considerably thickened, as is 

 shown in the side view, fig. 36, b. 



In fig. 37, a, h, is represented what I believe to be the full 

 grown state of the species. It at first view appears very distinct 

 from fig. 36 ; but on examination, we find the same thickening 

 of the middle and ends, and similar transverse lines. The two 

 varieties or states occur together ; both are also found fossil. 

 They are very abundant in ditches and ponds near West Point. 



3. Bacillaria manna? (PL II, fig. 38.) This is a »zaW«e species, 

 which I found at Stonington, Conn., and Staten Island, N. Y., ad- 

 hering to filamentous Algas. It is distinguished by having on each 

 half of its frustules two lines, which commence near the centre and 

 run straight nnd parallel, until they arrive near the extremities, when 

 they suddenly become falcate for a short distance, and then resume 

 their original directions. The curved portions of the lines have some 

 resemblance to the upper portion of a pair of tongs. The position 

 of these lines is very similar to those on Bacillaria Meneghinii. ( See 

 Schlechtendal's Linnsea, 1840, Tab. IV, fig. 1. 



TESSELLA. 



Free^ carapace simple, bivalve or multivalve {siliceous) pris- 

 matic, compressed inform of plates, forming- zigzag polypidoms 



