78 D. BRYCE ON A NEW CLASSIFICATION OF THE BDELLOID ROTIFERA. 



III. Family Microdinidae Murray 55 



Bdelloids with fully developed but non-revertile rostrum. 

 Corona absent or represented by few cilia about the mouth. 



1 genus. 



Microdina I\lurray 55 

 Toes four. 



M. paradoxa Murray 55 



Scepanotrocha rubra sp. nov. (PI. 2, Fig. 1.) 



Specific Characters : Hood-like expansion slightly convex, 

 without median notch or lateral projections ; hinder margin ex- 

 cised, merging into upper lip. Rami with six or seven fine teeth. 

 Spurs short blunt-looking cones, with small interspace. 



When creeping about, this species has some resemblance to 

 young examples of Hahrotrocha constricta (Duj.), especially if 

 coloui'less, yet may be distinguished by its more slender head and 

 general outline, its more uniform width, and the blunt-looking, less 

 divergent spurs. When newly obtained from moss-washings it 

 is exceedingly restless and marches about vigorously. After a 

 few days' isolation it becomes very quiet and displays its corona 

 quite freely. While feeding it remains affixed with the foot, and 

 does not drift about, nor does it readily move away. 



The outline of the " hood " is best seen in young individuals, 

 where it is distinctly broader than the corona, having a breadth 

 of about 24 fx, a depth of about 9 /u,. The lateral margins are 

 rounded off and the anterior is really slightly curved, but is fre- 

 quently sufficiently depressed to give the central jiortion a fiat 

 outline. Posteriorly the '' hood " merges into the upper lip, but I 

 have thought that I could now and again distinguish a faint but 

 boldly curved line marking the actual transition. Below the 

 " hood," the trochal discs appear to occupy the normal position, 

 having their planes about transverse to the body-axis, but the 

 cilia on the dorsal portions of the discs are comparatively feeble, 

 and the "cog-wheel" appearance is only presented by the cilia 

 on the ventral portions. The short pedicels are approximate but 

 distinct. The "[cheeks," or lateral cushions of the mouth, are 

 thickened, externally and ventrally prominent, and somewhat 



