294 Sketch of the Infusoria of the family Bacillaria. 
I have noticed in several species groups of molecules moving 
actively, precisely like those seen in Closterium. | Indeed this 
genus is most closely allied to Closterium, and some forms oecur 
which show a complete transition from one genus to the other. 
(See remarks under the head Closterium.) 
_ Capt. Carmichael, with his usual acuteness, detected their ani- 
mal nature. He remarks of two of the species, “ these are ani- 
mals instead of plants, if the faculty of locomotion will entitle 
them to that rank.’”” (See Hooker’s British Flora, V, p. 398.) I 
have frequently noticed the motion of several species; it is quite 
as distinct as in Closterium. 
1. Ewastrum rota, Ehr. (Fig. 22, Pl. 1.) Body binary, lenticular, 
discoid, smooth, the edges dentate or spiny, 3, to 75 line. Echinella 
rotata? Greville. 
The species represented in our figure appears to be the Z. rota 
of Ehrenberg; and agrees pretty well with the account given by- 
Greville of his Echinella rotata, which he describes as having 
the “frond plane, circular, divided by a line passing through the 
centre, each portion composed of radiating segments cleft nearly 
to the central line.” (See Brit. Flora, V, p.398.) Having seen 
no figures of the European species, I cannot be sure of their 
identity with ours. 
The species represented in fig. 22, is quite common in the 
United States. I have seen it in Rhode Island, New York, Vir- 
ginia, and Ouisconsin; I have generally found it scattered among 
Conferve, but I once in early spring found many hundreds of 
them ¥olected together on the bottom of a very small pool of 
water ina sphagnoiit bog. Some variety occurs in the outline ; 
thus the two large ebsieat portions of each half are often perfectly 
symmetrical, and not unfrequently dentate near the ends. I have 
seen specimens twice the size of the one represented. 
2. Euastrum crux melitensis. (Fig. 23? Pl. 1.) Body binary, len- 
ticular, discoid, smooth, - edges deeply divided into six dentate an 
spiny rays. 
I copy this Siseériplitin. that it may be compared with fig. 23, 
Pl. 1, which represents a very beautiful form which I have found 
in various situations near West Point, and also at Staten Island. 
Lhave seen it move i 
~ 8: Euastrum ——. (Fig. 24, Pl.) ‘This i possibly only @ 
younger state of B, rota, (fig. 22) with which it oecurs. 
