HELBOPEEA SPHAGNI. 145 



The examples figured on Plate XXX show the extent 

 of- variation of this, the largest and most handsome of 

 the Heleoperas, in widely-separated localities, one in the 

 lowlands of Cheshire, the other a sub-alpine district in 

 Merionethshire. The most striking variation, perhaps, 

 is in the mouth. In both cases the lips are thin and 

 closely approximated. So thin are they in the Cheshire 

 examples that during encystment the outline of the 

 mouth (in broad view) is lost and the chitinous mem- 

 brane is thrown into folds and wrinkles. "We have not 

 seen any encysted example from Merionethshire, but 

 in all living ones the mouth is clearly defined, and 

 apparently of more solid substance, so that there is 

 less likelihood of its presenting any modification under 

 other conditions. In these, it will be observed from 

 the figures that the broad convex base contrasts rather 

 remarkably with the narrower and less convex mouth 

 of the Cheshire examples. That figured (PI. XXX, 

 figs. 6-8) may be assumed to be a young individual; 

 the test was very transparent, lightish yellow, with a 

 reticulated surface, and a crown destitute of sand- 

 grains; the animal was very active, the plasma crowded 

 with bright green chlorophyllous matter, and the 

 pseudopodia — flexible, sometimes bifurcated and con- 

 torted—were thicker than those from the Welsh 

 locality. In narrow lateral view the test was narrowly 

 ovoid, the mouth showing as an acute notch. When 

 turned directly to the eye (in transverse section) the 

 mouth presented the appearance of a narrow slit, with 

 acute ends. Some empty tests were found, at Knuts- 

 ford, a darkish purple in colour, with the ordinary 

 surfacing combined with an admixture of quadrangular 

 scales similar to those of Quadrula symmetrica. 



The Merionethshire examples, besides exhibiting 

 the peculiarities in broad view which we have pointed 

 out, were more compressed, and in transverse section 

 the ends of the ellipse were more narrowly obtuse, 

 giving that section an outline which might almost be 

 described as lenticular. 



VOL. ir. 10 



