36 THE ROTIFERA 



in clean ponds round about London, and Mr. Hood has met with it in the Perthshire 

 lochs. 



The Notommatada and PhilodinadcB have a very wide range. The algae of ponds 

 always hold many species, and many haunt the sediment, that lies on the mud of the 

 bottom. Some of the latter are to be found in gutters of houses, in water-butts, on the 

 blades of wet grass, anywhere indeed where dust can fall and moisture can follow. For the 

 eggs of the Rotifera are blown away by the wind from dried-up puddles, and are scattered 

 broadcast through the air ; and some of the creatures they give birth to can exist appa- 

 rently under almost any kind of moist conditions. 



The Asph nclt net the fortunately are as indifferent to their quarters as they are large 

 and handsome. I have found them in roadside ditches thickly covered with Lemma, in 

 farmyard ponds, in the clear water of a miniature lake, and in a foul yellow-green duck 

 puddle in which the fluid (it could not be called water) was so thick that it had to be diluted 

 with five or six times its own bulk, before anything could be seen in it. An Asplanchna is 

 the very beau-ideal of a Rotiferon for a beginner. It is very large and transparent ; it swims 

 slowly ; and it generally occurs in great numbers. Moreover, its male is even more 

 transparent than the female ; a mere living bubble, thinner and clearer than the finest 

 blown glass. Unhappily, they are as capricious as they are charming; for a pool may be 

 full of them to-day and deserted to-morrow ; and, so far as my own experience goes, they 

 do not occur in the same spot year after year as many Rotifera do. 



The Pterodinadie and EiicJilanidiB are dwellers in clear ponds, and rather solitary 

 in their habits. On a warm sunny day the latter may be captured by skimming off the 

 Lemnm, and floating bits of leaves and stems, that are driven to the leeward corner of a 

 pool. If the bottle be then allowed to stand a few minutes till the water is clear, a 

 Euchlanis will often be found slowly gliding up the glass with its long toes pressed 

 against it. It is always worth while to capture it at once with a pipette, and put it into 

 a small tube along with any others of the same kind, as a live Euchlanis, properly ex- 

 hibited under dark-field illumination, is one of the choicest treats that the Rotifera afford. 



The PlerodinadcB are almost always creeping about the algre on the sides of the pond. 

 I never but once have seen any other than solitary specimens, but that exception was a 

 notable one. I then found swarms of them in the small space in which the sluice gate of a 

 pond worked. It was not more than a foot square by about four feet deep, and was mantled 

 over by duckweed. Out of this unlikely spot they were dipped by hundreds, while not 

 one could be found in the pond itself. Of course the duckweed came up with the Ptero- 

 dince, though as little as possible was taken, on account of the disagreeable way in which 

 it clings to every pipette put into the bottle. On this occasion, however, I found it of 

 great service ; for, on inspecting the catch at home with a hand-lens, I noticed that 

 the Rotifera were attached in clusters to some of the roots of the duckweed. Watch- 

 ing for a favourable opportunity, I whipped one of the Lemnm out of the water 

 so suddenly, that the creatures had not time to let go their hold. Then cutting off the 

 green head, I coiled the stem into a circle on a glass slip, and covered it with thin glass. 

 It was impossible to conceive a more beautiful sight than this natural cage now afforded 

 me. Thirty or forty shields of living glass were flashing across the field of view in every 

 direction ; some were adhering to the stem, swaying backwards and forwards so as to 

 present themselves in every point of view, while others were moored to the glass cover, 

 thus giving an admirable opportunity of making out their structure. 



It was a memorable occasion, but I never had such a chance again. 



I have yet to speak of the Synchcetadce among the free-swimmers. Both the genera 

 included in this family are to be found in open water ; and both alike shun dirty ponds ; 

 though in different degrees, for Synchmta is absolutely intolerant of them ; while I have 

 dipped up Polyarthra from the hollows of a muddy bottom where once a pond had 

 been. 



Both genera are tolerably common, and are often to be caught in considerable 

 numbers. The habits of the two chief species of Sijnchata, viz. S. mordax and S. 



