soria of the family Bacillaria. 101 
~~ Cocconets. 
"Free, single, carapace simple, bivalve (siliceous) prismatic or 
hemispherical, a single opening in the middle of both sides of 
each carapace (?), never double or catenate by spontaneous di- 
vision. 
1. Cocconeis? (Pl. 2, fig. 34.) Represents what I believe to be a 
species of Cocconeis. I found it adhering to a small marine Alga from 
the eastern shore of Florida. 
Beautiful figures of Cocconeis (Campylodiscus) clypeus, drawn 
by F. Bauer, will be found in Pritchard’s Hist. Inf., Pl. 12, fig. 
516—518. I have received fine specimens of thous. elegant fos- 
sils from E. J. Quekett, Esq., of London. 
Bacrivartia. 
Free, (never fired) carapace simple, bivalve or multivalve (sili- 
ceous) prismatic, forming chains or zigzag polypidoms by im- 
perfect a ico division of the carapace and perfect division 
of the 
% Ace oe paradova. (PI. 2, fig. 35.)—The standard bearer.— 
Striate, carapace linear, very ponents often fifteen times longer than 
broad, yellow, frustules very active, g's to Ay line. Syn, Vibrio paz- 
illifer, Muller. See Encyl. Meth. Pl. 3, fig. 16 to 20. 
I first detected this species in October, 1840, among Alge 
from the Hudson River, near West Point. I am jeddeserest by 
Dr. P. B. Goddard of Philadelphia, that it also occurs in abund- 
ance near that city. Itis a very interesting species, presenting 
by its curious motions and paradoxical appearance, an object well 
calculated to astonish all who behold it. At one moment, the 
needle-shaped frustules lie side by side, forming a ei 
plate ; suddenly, one of the frustules slides forward a little ways, 
the next slides a little also, and so on through the whole number, 
each however retaining a contact through part of its length with 
the adjoining ones. _ By this united motion the parallelogram is 
changed into a long line; then some of the frustules slide together 
again, so that the form is then much like a standard. Similar 
motions are constantly going on, and with such rapidity that the 
eye can scarcely follow them. ‘There are few more its ine 
objects for the microscope. 
_, Several of the positions of these singular productions.are. ail 
represented by Miller, (See Enc. Meth. Vers. Pl. fig. 16~20.) 
