80 BRITISH FRESHWATER RH1ZOPODA. 



they correspond with his description as to colour, 

 dimensions, and general structure. In none of the 

 individuals examined were pseudopodia visible; this 

 also agrees with Penard's observation as to the shy- 

 ness of the animal, and the infrequency of its display 

 of pseudopodal activity. When the plasma was pent 

 up within the test it filled the cavity, or nearly so. 

 Empty tests showed the colour very clearly. It was 

 generally a lightish yellow, not unlike that observed in 

 Ditrema, passing (presumably with age) into a brownish 

 tint resembling that of some diatoms. The test is 

 strongly compressed, much narrowed anteriorly in the 

 lateral view ; the margins are nearly straight. Two 

 individuals were found in conjugation. One test had 

 absorbed most of the plasma of the other, leaving it 

 more than half emptied. The nucleus was indistinguish- 

 able with a power of 480. 



C. NEBELINA. 



Genus 24. HYALOSPHENIA Stein, 1857. 



Hyalosphenia STEIN in Sitzber. bohm. Akad. Wiss. 1857, 

 p. 42. 



Test homogeneous, of varying outline, in lateral 

 view ovoid lengthways with sharply truncated mouth, 

 or pyriform with the mouth convex; membranous, 

 hyaline ; compressed in all except one species : the 

 crown uniformly arched. Plasma only partially filling 

 the test, and attached to it by threads or bands of 

 ectoplasm ; containing chlorophyllous particles in 

 varying quantity, usually one or two clear vacuoles, 

 and a nucleus (comparatively large) situated pos- 

 teriorly, but frequently obscured by food and other 

 granular material. Pseudopodia three to five, simple, 

 digitate, blunt. 



The genus is distinguished from Nebela by the homo- 

 geneous test. In two or three species the surface is 



