218 DAVID BRYCE ON THE 



and all the desired specimens picked out, the trough can be 

 emptied and refilled from the stock bottle and so on. If further 

 examination of the stock is to be deferred to another occasion, 

 I pour away gently the greater part of the remaining water, 

 and replace with clean water before placing the stock aside. 



I have not myself met with Fontinalis in the London district, 

 only in really hilly country. In some of the Epping Forest 

 ponds I have occasionally found masses of finer-leaved mosses, 

 which I have treated in the same way. 



A more easily obtainable moss is Sphagnum, which lingers on 

 in greatly reduced quantity in some parts of Epping Forest, 

 whilst on the moors of the north and west country it is generally 

 abundant wherever there is boggy ground. Although several of 

 the Rotifera which frequent this moss are also found in mosses 

 growing in dry situations, there are a few species, such as Hahro- 

 trocha angusticollis, H. lata, Scepanotrocha rubra, Stephanops 

 stylatus, S. tenellus and Distyla agilis, which are very rarely 

 found elsewhere. Besides these there are at least two species 

 that habitually live in those remarkably large cells which form 

 the cortical layer of the stems of the side-branches of 

 Sphagnum. Each of these cells is provided by nature with 

 an external opening, which admits the water within the cell- 

 cavity. In the dim ages of the past, Hahrotrocha Roe/peri and 

 HahrotrocTia reclusa have discovered the possibilities of such 

 cells for the purpose of shelter, and they have, in fact, become 

 tenants at will of these single-roomed, self-contained residences, 

 taking possession by simply squeezing through the doorway — 

 the natural orifice of the cell. Once inside, the rotifer finds itself 

 in sufficiently roomy quarters, where it can turn about, and if 

 all goes well, lay its eggs, and, so to speak, bring up its family, 

 living at peace and paying no rent. When it is hungry it pushes 

 its head and neck through the orifice and commences to feed. 

 To find these animals in situ it is necessary to strip the leaves 

 off the side-branch. It is not known definitely whether they 

 inhabit all kinds of Sphagnum. I have seen some forms in 

 which the cortical cells had openings which seemed too small 

 to permit the entrance of the rotifer. 



The general treatment of Sphagnum differs somewhat from 



