Sketch of the Infusoria of the family Bacillaria. 97 
is equally diffused in this country. I have myself observed it in 
Maine, Massachusetts, New York, Ouisconsin and Virginia. It 
is easily recognized by means of its large size and beautifully 
marked ventral faces. The striz seen on these faces may cor- 
respond to internal cells, but I believe them to be linear openings 
in the carapace itself, as may easily be seen on the fragments of 
fossil specimens. There are three rounded spaces on each ven- 
tral face, which I think have been mistaken for openings, but 
which appear to me to be thicker portions of the carapace. One 
of these spaces is in the middle, and the other two at the extrem- 
ities of the striated surfaces, and they are connected by a very 
delicate double line (canal?) A similar structure is seen on sev- 
eral other species of Navicula, Cocconema and Gomphonema. 
The real orifices are shown at ¢, ¢, c, c, in our fig. 16, 6. Moving 
particles somewhat like those of Closterium may sometimes be 
seen near the extremities. In fig. 17, a, b, Pl. 2, I have copied 
from Ehrenberg, (Die Fossilen Infusorien und die lebendige Dam- 
merde, Berlin, 1837, Pl. 1, fig. 19,) a sketch in which he repre- 
sents the organs of motion, the stomach &c. of this species. The 
reference letters having been omitted by the engraver of Ehren- 
berg’s plate, I have been obliged to insert them according to what 
I believe was their intended position. 
~The following is a Manslation: of Ethsenberg’ s explanation of 
this figure. (See fig. 17, Pl. — 
‘A living specimen of ‘Navicols visite 3 in ‘winch by the i injec- 
tion of indigo are distinctly to be seen; the stomach v, the two 
great spherical sexual glands s s, and the lamelliform extensions 
of the green ovarium, 0’ mouth opening, o’ sexual opening? 
a, a, a, a, four movement openings, p the pediform organs of mo- 
tion. ‘The visible currents on the body, both when creeping and 
at-rest, are denoted by arrows.” 
2. Navicula viridula. Carapace straight, lanceolate, linear, very 
slender, truncate at the ends, flattened on one side, lanceolate and ob- 
tuse on the other, 13 to 15 strie in 735 pete ziytoyyline. Frustulia 
viridula, Ktz., Linn. 1883, Pl. 18, fig. 1 
_Ebrenberg meutions this as one of Ha species detected by him 
among fossil infusoria from West Point. Kutzing’s figure does 
not allow me to determine with certainty, which of the various 
at West Point, pacnes to this species, 
Nol. x xu, No. 1.—Oct.—Dec. 1841. 13 
& 
