198 0. BKYCE ON TWO NEW SPEClKt? OF 



these lobes a collar-like ridge, the dorsal continuation of the 

 margin of the mouth. By measuring the greatest breadth, 

 across the two fully expanded lobes, and again at the edge of 

 this collar, we can classify, with some accuracy, the varying 

 proportions of the ciliary organs. 



In Philodina the two discs are usually much wider than the 

 collar, but as we examine the Callidinse we find a series of 

 gradations passing from the broad Philodina-like discs of 

 quadricornifera and other large forms until we reach, in this new 

 species, Callidina pusilla, a form in which the discs are barely 

 one-half the brea^dth of the lip margin. It is no longer the 

 collar which we can measure, we have to take our dimension 

 from side to side of the lip itself. The conspicuous gap between 

 the lobes has disappeared, and there remains but a shallow 

 notch, merging into a shallower groove, to mark the two-fold 

 structure of the almost united discs. The cilia of the principal 

 wreath no longer produce the appearance of a revolving cog- 

 wheel, but rather that of so many lashes, whose free ends are 

 rapidly and independently whirling in circles as though swung 

 round from their respective bases, an appearance probably as 

 illusory as the other. They give the impression of being rather 

 longer and more vigorous, if possible, than usual, as though to 

 compensate for their presumably smaller number. I have not 

 observed the animal attempt to swim, but these cilia, at all 

 events, have no difficulty in fulfilling their important duty of 

 drawing food particles within reach of the secondary wreath. 

 In consequence of the reduced proportions of the discs, and the 

 retained height of their pedicels, the secondary wreath is 

 placed, as to the principal wreath, at a much more oblique 

 angle than is normal. The species which approaches this most 

 nearly in its restricted disc surface is C. reclusa, one of the two 

 interesting species found dwelling in the cells of Sphagnum, 

 and it is curious to note that pusilla is also a tube-dweller ; 

 indeed, it was this species which I referred to in my earlier 

 paper as a tube-dwelling species, which I could not identify. 



Recently, however, I have succeeded in establishing a colony 

 in a trough whose sides have become coated with a growth of 

 some very minute alga. Here and there specimens of pusilla 

 have formed little tubes, distinguishable by their brown 

 colour from their floccose-like surroundings. It is almost a 



