88 PROCEEDINGS OF THE ACADEMY OF 



The interesting reseai'ches of Prof. Richard Greef, of Marburg, 

 published iu the second volume of Schultze's Archiv f. Mikros- 

 kopische Anatomie^ on Araoebse living in the earth (Ueber einige 

 in der Erde lebende Amoehen, etc.), led me to look in similar 

 positions for Rhizopods. 



In the earth about the roots of mosses growing in the crevices 

 of the bricks of our city pavements, in damp places, besides find- 

 ing several species of Amoeba, together with abundance of the 

 common wheel-animalcule, Rotifer vulgaris, I had the good fortune 

 to discover a species of Oromia. I say good fortune, for it is 

 with the utmost pleasure I have watched this curious creature for 

 hours together. The genus was discovered and well described 

 by Dujardin, from two species, one of which, G. oviformis, was 

 found in the seas of France ; the other, the G. Jiuviatilis, in the 

 River Seine. 



Imagine an animal, like one of our autumnal spiders stationed 

 at the centre of its well-spread net ; imagine every thread of this 

 net to be a living extension of the animal, elongating, branching, 

 and becoming confluent so as to form a most intricate net; and 

 imagine every thread to exhibit actively moving currents of a 

 viscid liquid both outward and inward, carrying along particles 

 of food and dirt, and you have some idea of the general character 

 of a Gromia. 



The Gromia of our pavements is a spherical cream-colored 

 body, about the -i-^th of a line in diameter. When detached from 

 its position and placed iu water, in a few minutes it projects in 

 all directions a most wonderful and intricate net. Along the 

 threads of this net float minute naviculae from the neighborhood, 

 like boats in the current of a stream, until reaching the central 

 mass they are there swallowed. Particles of dirt are also col- 

 lected from all directions and are accumulated around the animal, 

 and when the accumulation is sufficient to protect it, the web is 

 withdrawn and nothing apparently will again induce th animal 

 to produce it. 



From these observations we may suppose that the Gromia 

 TERRicoLA, as I propose to name the species, during dry weather 

 remains quiescent and concealed among accumulated dirt in the 

 crevices of our pavements, but that in rains or wet weather the 

 little creature puts forth its living net which becomes so many 

 avenues along which food is conveyed to the body. As the 

 neighborhood becomes dr}', the net is withdrawn to await another 

 rain. The animal with its extended net can cover an area of 

 nearly half a line in diameter. The threads of the net are less 

 than the ^otoo^^ ^ ^^^ inch in diameter. 



Bemarks on the Revimjication of Rotifer vulgaris Prof. 

 Leidy remarked that during the search for Rhizopods, having 

 noticed among the dirt adhering to the mosses in the crevices of 



