120 F. W. PHILLIPS OBSEKVATIONS OX ROTIFERS. 



dust, which soon accumulates and is very difficult to get rid of. 

 They should have for soil one inch of river-mud covered with half 

 an inch of sand. It is best to plant only such plants as have fine 

 leaves, as Myriophyllum, for this renders easy the examination of 

 those species which attach themselves to leaves permanently or 

 temporarily. A small quantity of the starwort, Lemna minor and 

 L. trisulca, may float on the surface, and a few stalks of hay 

 should be placed in the water to favour the growth of monads, 

 which form the principal food of the Rotifera. 



The greatest enemies of an infusorial aquarium are the Entomo- 

 straca (especially the genus Cyclops), which should be carefully 

 eliminated ; but this is sometimes a difficult task owing to their 

 great activity and the rapidity with which they multiply. I 

 always keep a few minnows wliich I turn in when Entomostraca 

 gain ground, and take out again when their numbers are thinned. 

 Care should also be taken to remove all snails, as when browsing 

 on the Confervse they are apt to disturb the eggs which are 

 frequently deposited thereon. 



The tube-bearing rotifers thrive best in a shady position, whereas 

 most of the free-swimmers love light, and Cojiochilus (the most 

 delicate of all rotifers) may be kept for a long while if exposed lo 

 the open air in a place where it receives plenty of light without 

 coming under the influence of direct sunlight. 



Many species of Rotifera, besides those I have mentioned, have 

 come under my observation, but I have been unable to make 

 sketches of them, and I fear also that I have already trespassed 

 too much upon your time and patience ; but I should like to draw 

 your attention to two localities peculiarly productive. The first is 

 the marsh land at the back of the College Arms at Hertford Heath ; 

 this is extremely rich in Desmidieae, Diatoms, Protophytes, and all 

 light-loving animalcules. The other is a pond in the "Wood- 

 lands," Hoddesdon (rich in Polyzoa and all thecated Rotifera), 

 from which I have at various times received collections of Infusoria 

 through the kindness of Miss Warner ; and it is to her courtesy 

 that I am indebted this evening for many of the living specimens 

 shown under the microscopes. 



In conclusion, I would urge upon all our members who study 

 pond-life to make systematic notes of all species found, recording 

 the localities from which they are obtained, and the dates of 

 capture. I see no reason why we should not have the same accu- 

 rate records of the microscopic fauna as we have of the geology 

 and botany of the county. We are faiidy strong in microscopical 

 observers, the field is new, and it offers attractions of the most 

 fascinating kind. 



