1895.] MICROSCOPICAL JOURNAL. 5 



of animalcule heedless enough to come in contact with 

 their tentacles. Hydra is sometimes observed, stub- 

 bornly holding on to a Nais worm larger than itself, 

 and the spectacle is entertaining as well as exciting. 

 Usually the Hydra conquers. 



Of genera included under the Rhizopoda, quite a num- 

 ber are found. Arcella and Difflugia are not infrequent, 

 but seldom appear in large numbers. Difflugia urceolata 

 and spiralis (Leidy), have been found, and several of 

 the last species appeared in pairs joined mouth to mouth 

 just as he describes and figures them. Cyphoderia, 

 Nebela and Euglypha have also been detected. 



Gromia oviformis, of which a drawing from a sketch 

 made at the time is shown in Fig. 2, was found over a 

 year ago in the mud from a tank. This is most unique 

 and instructive as being the only fresh-water representa- 

 tive of the Foraminifera, which occur in such immense 

 numbers in the Ocean and form vast deposits at the bot- 

 tom thereof. Grromia as found in the conservatory had 

 a test or shell of a dirty white color, sometimes inclin- 

 ing to yellow. The pseudopoda were thrown out in 

 numerous filaments far finer than spider lines ; often an- 

 astomosing, and filled with minute bodies traversing 

 back and forth. The filaments were often more thickly 

 crowded than shown in the drawing. The mouth is not 

 always well displayed, as it is the habit of the animal to 

 collect a mass of mud or debris there. The writer de- 

 tached this mud from several, but the next day found 

 that every one of them had buried its mouth in mud 

 again. 



There is surely a reason why Foraminifera are not 

 permitted to abound in fresh-water bodies. It is easy 

 to discern that in the ocean they subserve a useful pur- 

 pose depositing much of the soluble carbonate of lime 

 it contains, and that the great beds of their dead shells 

 now forming may in future ages be elevated to the sur- 



