170 



THE AMERICAN NATURALIST [Vol. LI 



viridis. The only other forms present were but very few 

 Colpoda campyla and Cyphoderia ampulla. 



Several samples were taken from leaves and grass 

 frozen together, lying beneath three inches of solidly com- 

 pacted snow in a small oak grove not far from a ravine 

 through which flowed a perennial stream. This material 

 was allowed to stand in its own snow in a cotton-tamponed 

 jar until the snow had melted and the resulting water had 

 attained room temperature, cir, 72° F. 



The Amoeba proteiis were more abundant than I had 

 ever seen them before except in artificial cultures. Not 

 infrequently as many as ten individuals could be counted 

 at once in the field of the 10 mm. objective. The other 

 predominant forms were : 



Holostichia vemalis, abundant. Opalina ranarum, several 



Monas irregularis, abundant. Paramcecvum caudatum, several 



Other forms present in less numbers (few or rare) : 



Astasia lagenula . Paranuxcium trichium 



OiJcomonas sp, Platyrichotus opisthobolus 



Catalogue of Species Noted with Measurements in 

 Microns 



In each case length refers to the antero-posterior axis, 

 except with globular or subglobular forms when it refers 

 to the diameter of the body. All dimensions are given in 

 microns (=1/1000 mm.). 



It is interesting to recall, in connection with the sizes of 

 these organisms, that the diameter of the average human 

 hair is 100 1 



