124 SKETCH or THE INFUSORIA 



I copy this dcscriplion, that it may be compared witli fig. 23, 

 PI. I, which ivprosents a very beauliful form which I have foimd 

 in various silualions near West Point, and also at Stalen Island. 

 I have seen it move distinctly. 



3. Euastrnm . (Fig. 24, PL I.) This is possibly only a 



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



4. Euastrnm . (Fig 2;"), PI. T.) This very elegant form is 



somewhat rare. It occm's at West Point with the preceding. 



5. Euastrum . (Fig. 2G and fig. 27, a, h, c, and d, PI. I.) I 



suspect that the s])ecies represented in figs. 2G and 27, is the same 

 as the Echwdki oblonixa of Greville, which he describes as being 

 " compressed, oblong crenato-pinnatifid, and lobcd, divided trans- 

 versely almost to the centre." (Brit. Flora. Vol. V. p. 398.) 



Fig. 27, a and h show two positions of the same individual; 

 cand d show small individuals, which are probably the young of 

 this species. Fig. 26, although much more deeply lobcd than 

 fig. 27, is probabbj only an older state of the same. They occur 

 at West Point, also near Detroit, jMichigan, and in Ouisconsin. 



6. Euastrum . (Fig. 28, a, h, PL I.) This species is neither 



lobed nor undulate ; but while the general outline is convex, a mi- 

 nutely serrated edge may be seen. When thrown on its side, (fig. 28, 

 h,) it presents an unusual thickness. 



If this species is compared with fig. 38, PI. I, the close rela- 

 tion existing between the genera Clostcrium and Euastrum will 

 be manifesl. 



7. Euastrum . (Fig. 29, PL I.) I suspect that the bodies 



represented in fig. 29, belong to this genus. They consist usually of 

 four somewhat elliptical green bodies placed parallel to each oilier, 

 and uniied laterally, as seen in the figure. Each elliptical portion is 

 bidentate at the ends. I have met with specimens in which eight 

 such corpuscles were united, producing such an appearance as would 

 be given if a figure, like that shown in fig. 29, had a similar one added 

 immediately below it. 



If this is a species of Euastrum, perhaps it may be thus char- 

 acterized ; Euastrum . Fig. 29. Binary (or sometimes 



quaternary,) each corpuscle divided by deep lateral sinuses into 



