294 Sketch of the Infusoria of the family Bacillana. 



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 occur 

 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. Euastrum rota, Ehr. (Fig. 22, PI. 1.) Body binary, lenticular, 

 discoid, smooth, the edges dentate or spiny, J^ ^o -jV line. Echinclla 

 rotata ? Greville. 



The species represented in our figure appears to be the E. 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 Hne." (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 

 Confervas, but I once in early spring found m^any hundreds of 

 them collected together on the bottom of a very small pool of 

 water in a sphagnous bog. Some variety occurs in the outline ; 

 thus the two large central 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, the edges deeply divided into six dentate and 

 spiny rays. 



I copy this description, that it may be compared with fig. 23, 

 PI. 1, which represents a very beautiful form which I have found 

 in various situations near West Point, and also at Staten Island, 

 I have seen it move distinctly. 



3. Euastrum . (Fig. 24, PI. 1.) This is possibly only a 



younger state of E. rota, (fig. 22,) with which it occurs. 



