126 Transactions. — Zoology. 



posterior of the body, but from its ventral side, about two- 

 thirds of the way back. There is a special little knob-guarded 

 aperture from which it protrudes, and through which it is often 

 wholly retracted. It consists of only one joint, protruding 

 only a short distance beyond the knobs spoken of above, and 

 ending in two toes a little longer than the foot itself. The 

 head is small, and not well defined from the rest of the body. 

 It is rounded off in front, and is, hke the foot, entirely retrac- 

 tile within the lorica. Cilia fringe all its anterior face ; they 

 are of medium size and rather slow motion. The lorica is, of 

 course, peculiar. Instead of spines it goes in for knobs. 

 Two blunt ones project above and below the head, and two 

 more smaller and better-defined ones project in front of and 

 behind the aperture for the foot. The anterior edge is well 

 defined, and the whole of the rest of the body is encased in 

 this hyaline shell, except for the small ventral foot-hole. The 

 lorica seems fairly dense, especially behind, where it com- 

 pletely closes in the posterior of the animal. The dorsal cleft 

 is very distinct when carefully looked for ; it is exceptionally 

 deep, narrow, and well defined. The mastax is of the forcipate 

 type common to the Salpinidaeans and Notommatadaeans. It 

 is, however, very small and slender, and so rather difiicult to 

 draw. The pincer-like portions of the rami are very long, and 

 protrude in front of the rest of the mastax. The ahmentary 

 canal is of large proportions, and passes along the dorsal part 

 of the body, then round the posterior part, and for a short 

 distance along the ventral side, till it reaches the posterior 

 junction of the foot and body. It was filled with rounded 

 yellowish masses of food-matter, and was considerably dis- 

 tended. The brain is of fair size, and is situated near the 

 dorsal surface, about one-third of the way back from the head. 

 Its anterior veneer is coloured with a red pigment answering 

 to the eye, which, as far as position goes, bears the same 

 relation to the brain as the peel of half an orange bears to the 

 orange. I saw nothing of the other internal organs. 



Movement, fairly brisk, though not so brisk as to make 

 the drawing difficult. Like other compressed Eotifers, it 

 swims on its side almost exclusively while under the cover- 

 glass, though I suppose there is little doubt that it swims 

 upright when in its natural conditions. The head and foot 

 are retracted as wholes with fair frequency. 



Hab. The pool. 



Rather rare. 



XII. Postclatisa circularis, sp. nov. Plate X., figs, xii., xii.a. 



Specific characters: Body greatly flattened from side to 



side. Outline of body from the side almost circular. Lorica 



not very firm ; front edge imperceptibly dwindling away. Only 



