240 GEOLOGY OF THE FIRST DISTRICT. 
Gomphonema acuminatum? (PI. 42, fig. 6.) Striate; corpuscles elongated; wedgeform, end swollen 
and pointed, contracted on the side. 
The small species (fig. 6) agrees pretty well with the above characters. It is common in 
ponds near West-Point. I have also seen it in several American specimens of fossil infusoria. 
Gomphonema -. (PL 42, fig. 7.) Frustules smooth, geminate or in fan-shaped groups; one side 
elongated, wedge-shaped, truncate; the other side obovate; pedicel repeatedly dichotomous. Ma¬ 
rine. 
I have examined this species only in a dry state, having first noticed it on a glass slide on 
which I had preserved some specimens of Echinella flabellata from Stonington, Conn. The 
figure is drawn from the dry specimens. 
Echinella, Ehr. Carapace simple, siliceous ; fixed at one extremity to a pedicel; wedgeform, longer 
than broad, fan-shaped or verticillate by spontaneous division. 
Echinella flabellata. (Pi. 42, fig. 8.) Smooth; corpuscles linear, cuneiform, truncate, slightly three¬ 
toothed, stride longitudinal, line without the pedicel. Licmophora flabellata, Ag. (Greville 
in Hooker’s English Flora, Vol. 5, p. 408.) 
This beautiful marine production presents, in its fan-shaped groups of crystal-like corpus¬ 
cles, an exceedingly elegant appearance. The fans are supported by long flexible clavate 
pedicels, which are grouped together in large bunches covering filamentous marine algae and 
zoophytes. 
I found it quite abundant at Stonington (Conn.), in July. It is said to occur also in Scot¬ 
land, Venice, and at the Cape of Good Hope. 
Echinella -. (PI. 42, fig. 9.) Corpuscles smooth? lanceolate, truncate; pedicel short, broadly 
clavate, often nearly circular, supporting the radiating closely aggregated corpuscles. 
I detected this very elegant species about a year since in the Hudson river near West-Point, 
where it grows upon Potamogeton, Enteromorpha, etc. It agrees in many respects with E. 
fulgens, Grev.; but that is described as being striate, a character which I have not perceived 
on our species. 
CoccoNEMA. Carapace simple, bivalve or multivalve, siliceous ; fixed by one end, pediculate, longer 
than broad; pedicel in the direction of the axis of the body. {^Pedicellate Naviculce.) 
When separated from their footstalks, there is no good character to distinguish them from 
Navicula, but the unsymmetrical boat-shaped frustules of Cocconema will generally serve to 
identify them. 
Cocconema -. (Pi. 42, fig. 10.) Carapace lanceolate, ends obtuse, pedicels repeatedly dichoto¬ 
mous, secondary branches articulated to the primary ones. Striae were not perceived. 
Abundant in the Hudson river at West-Point. It appears to be allied to C. lanceolatum of 
Agardh. 
Cocconema -. (PI. 42, fig. 11, a, b.) These figures represent two positions of a species of 
Cocconema which is very common in the living state near West-Point, and which also abounds as 
a fossil. In the living state, I have but rarely seen it attached to a pedicel. It is generally free, 
and moves about spontaneously like a Navicula. 
