PLACES WHEEE EHIZOPODS MAY JBE POUND. 9 



usually black mud, which indeed is almost universally devoid of life of 

 any kind. 



Rhizopods also occur in the flocculent materials and slimy matter 

 adherent to most submerged objects, such as rocks, the dead boughs of 

 trees, and the stems and leaves of aquatic plants. A frequent position is 

 the under side of floating leaves, such as those of the Pond- lily, Nymphcea 

 odorata; the Spatter-dock, Nuphar advena; and the Nelumbo, Nelumbium 

 luteum. Certain kinds of Rhizopods, especially the Heliozoa, or Sun-ani- 

 malcules, are most frequent among floating plants, such as Duck -meat, 

 Lemna; Horn wort, Ceratophyllum ; Bladderwort, Utricularia; and the 

 various Confervas, as Zygnema, Spirogyra, Qscillatoria, and the Water-purse, 

 Sydrodietyon. 



In no other position have I found Rhizopods of the kind under con- 

 sideration in such profusion, number, and beauty of form as in sphagnous 

 bogs, living in the moist or wet Bog-moss, or Sphagnum. Sometimes I 

 have found this particular moss actually to swarm with multitudes of these 

 creatures of the most extraordinar}'- kinds and. in the most highly developed 

 condition. A drop of water squeezed from a little pinch of Bog-moss has 

 often yielded scores of half a dozen genera and a greater number of species. 

 Frequently, however, the Sphagnum of many localities contains compara- 

 tively few Rhizopods, though I have rarely found them entirely absent 

 from this moss. Other mosses and liverworts I have not observed to be 

 specially favorite habitations of the Rhizopods, not even such aquatic kinds 

 as the Fontinalis. 



Notwithstanding the experience of four years' exploration and obser- 

 vation, I have not been able to determine the exact conditions under which 

 particular Rhizopods are to be obtained with certainty and in any consid- 

 erable numbers. In general, they are to be found in greatest number and 

 variety under the peculiar conditions favorable to them, in old established 

 ponds, bogs, etc., which are not liable to become completely dried up in the 

 summer season. At times, however, I have found a profusion of one or 

 two forms in some localities, in which, in another season, I could find but 

 few or none. Sometimes I have found many individuals of a particular 

 kind in a shallow pond of recent origin, which, after drying up in the 

 sunamer and being renewed the following spring, yielded no more of the 

 same. Sometimes the most unpromising places have produced an unex- 



