122 



THE AMERICAN MONTHLY 



[Jniy, 



eral, small, distributed near the pe- 

 riphery ; nucleus spherical, subcen- 

 tral. Diameter of body j-^-q^ to j-^^q 



Fig. 20. — New Fresh-Water Infusoria. 



inch. Habitat. — Shallow ponds in 

 early spring. 



This remarkable combination of 

 rhizopod and infusorian was abun- 

 dant in the first gathering made in 

 early spring from a shallow little pool 

 near a country wayside. Green algae 

 were already a conspicuous feature of 

 the surface, and their flagellate spores 

 quite as conspicuous constituents of 



the water when in the field of the mi- 

 croscope. On these active germs the 

 actindmonas was so greedily feed- 

 ing that its endo- 

 plasm was usu- 

 ally crowded 

 and colored by 

 them. In this 

 matter of taking 

 food it has de- 

 cidedly the ad- 

 vantage of its re- 

 latives higher in 

 the scale of life, 

 since the act can 

 be performed in 

 either the seden- 

 tary or the freely 

 motile condi- 

 tions. In the 

 former the pseu- 

 dopodia are 

 entirely with- 

 drawn, and food 

 is then engulfed 

 at any point on 

 the surface, be- 

 ing taken with a 

 large drop of 

 water, as is com- 

 monly done by 

 so many of 

 the mouth less 

 forms. 



The move- 

 ments in the 

 rayless state are 

 comparatively 

 slow and irregu- 

 lar, consisting of a revolution on the 

 longitudinal axis, with sudden changes 

 of position, and with a frequent, 

 rapid, but not long continued trem- 

 bling or shivering of the entire body, 

 very little space being traversed by 

 its efforts, the motions not being those 

 of the gigantic monas which the in- 

 fusorian then closely resembles. When 

 in this monadiform condition it is 



Explanation of Figures. 



Fig. I. ActinSttionas vernalis X 750. Fig. 7. tothumia plectSstyla X 275. 



Fig. 2. Bicoixcadissimilis y. J20. Fig. 8. Cothiimia bipdrtita Y. 225. 



Fig. 3. B. acuminata X 720. Fig. 9 Cothuinia bipartita. Variety with elliptical 

 Fig. 4. MallSmonas liidinesutn X 750. aperture 



Fig. 5. I.acrymaria vSrtens X 180. Fig. lo. Foiiophrya macrdstyla X 250. 

 Fig. 6. Lagynus lasius X 312. 



