134 BEITISH FEESH WATER EHIZOPODA. 



Test chitinous, variable in size and contour ; usually 

 carrying from four to six well-developed, curved, 

 and occasionally bifid spines ; opaque or semi-trans- 

 parent, with an irregularly margined orifice, and not 

 infrequently covered wholly or partially with fine 

 sandy particles, or diatom shells ; the excentric 

 mouth being always at the shallow extremity. Endo- 

 plasm and pseudopodia as in Difflugia ; the latter 

 sometimes knotted or branching. 



When encisted the protoplasm forms a spherical 

 ball in the thicker part of the test ; it is filled with 

 granular matter and green or colourless globules. 



Dimensions variable: Diameter of test 110-150 /A; 

 length of spines 20 n or more. Diameter of mouth 

 50-60 /A. 



In ponds and ditches and amongst Sphagnum and 

 wet moss, associated with Difflugia, etc. ; frequent. 



The species may readily be distinguished from 

 Difflugia constricta by its larger size and more ex- 

 panded outline, as well as by the branching of the 

 pseudopodia. It is usually most plentiful amongst wet 

 Sphagnum in swampy ground. Examples occurring 

 in such situations are, as a rule, free from extraneous 

 matter, except diatom shells, of which in some cases 

 they appear as if built up. Those without incrusta- 

 tions have an irregular and delicate mesh-work on the 

 cliitinous surface and usually have the longest spines. 



Examples vary greatly in size. West (in ' Journ. 

 Linn. Soc.,' Zool., vol. xxviii) records individuals from 

 Athry Lough, W. Ireland, measuring 450 p, without 

 the spines. The transparent cliitinous test sometimes 

 exhibits a cancellated or punctated surfacing. Some 

 Terrington Carr examples were found by the same 

 author to be of a pale yellow colour and minutely 

 scrobiculate. The scrobiculations were irregularly 

 disposed, being scattered more or less in groups, 

 and between them were numerous much smaller 

 puiictulations. 



