HYALOSPHKNIA PLATYSTOMA. 87 



Trudui S.-Peterb. Obshch. XXXYI (1906), 2, p. 230; 

 SCHROUTEDEN in Ann. Biol. Lacustre, I, 3 (1906), p. 352. 



Rather larger than the preceding species ; test 

 consisting of a colourless transparent chitinoid mem- 

 brane ; ovoid in front view with a semi-circular 

 apex and a widely-truncate base ; the sides slightly 

 convex and the mouth very wide ; in side view 

 narrowly ovoid, with no trace of a constriction 

 towards the apex, slightly notched at the mouth. 

 Protoplasmic body held in position by several fine 

 strands passing to the inner surface of the test ; 

 inferior part clear; the superior part granular and 

 filled with food-particles ; nucleus dorsal and promi- 

 nent ; contractile vacuoles not observed ; pseudopodia 

 two, short and lobose. 



Dimensions : Length 40-42 /x, ; breadth 28-32 /x. 

 Near Tarbert, Harris, Outer Hebrides (West). 



Prof. Gr. S. West (whose description we quote) says : 

 " Numerous active specimens of the above species 

 were observed in a collection from a Sphagnum- 

 bog. The small size of the shell and the extremely 

 broad mouth are features which easily distinguish it. 

 In the side view there is no trace of a constriction 

 towards the apex of the shell, and there is a distinct 

 line of demarcation between the lower part of the 

 body-protoplasm, which gives origin to the pseudo- 

 podia, and the upper granular portion." The author 

 points out that as compared with H. minuta the form 

 of the shell is different, the mouth being much broader 

 and more truncate ; and the body-protoplasm and 

 pseudopodia exhibiting rather different characters. 



6. Hyalosphenia subflava sp. nov. 

 (Plate XXXI, figs. 9-12.) 



Test resembling, in general form, that of H. minuta, 

 but larger, and differing from it also in being of more 

 substantial - looking texture ; chitinous, compressed ; 



