52 BRITISH FRESHWATER RHIZOPODA. 



HoNiGMANN in Abh. Mus. Magdeburg, II (1909), p. 62. 



HoPKiNSON in Irish Natur. 1910, p. 3. 



Wailbs & Penaed in Proc. R. Irisb Acad. XXXI, lxv (1911), pp. 



15, 21-22. 

 Wailbs in Scott. Natur. 1912, pp. 60. 62 ; in Jrn. Linn. Soc, Zool. 



XXXII (1912), pp. 126, 150; in Naturalist, 1913, p. 147. 

 Schmidt in Arch. Protist. XXIX (1913), pp. 221, 226. 

 AssuUna semilimum 

 Pbnaed in Mem. Soc. Geneve, XXXI, 1, n (1890), pp. 175-176, pi. 



viii, fi. 68-90 ; in Jahrb. nassau. Ver. Naturk. XLIII (1890), p. 71 ; 



in Amer. Natur. XXV (1891), pp. 1074, 1079. 



Test moderately large; brown or colourless; in broad 

 view pyriform, ovoid, or sub-circular, compressed ; 

 transverse section lenticular ; composed of imbricated, 

 elliptical, silicious scales ; aperture oval, bordered by a 

 thin chitinous membrane, with undulate or irregularly- 

 dentate margin ; nucleus large, containing two to six 

 nucleoles; plasma not entirely filling the test, granular^ 

 usually containing numerous food-particles ; one con- 

 tractile vesicle usually present and numerous vacuoles ; 

 pseudopodia few, straight, divergent, slender, seldom 

 branched. 



Length usually 60-90 /a, but may attain 150 /u.; 

 breadth 50-75 /a; aperture 16-25 ju,; thickness about 

 two fifths of the breadth. 



Habitat. — Sphagnum and mossSs in marshy situations. 



Generally distributed in the British Isles. It is 

 found at considerable elevations, e. g. Lochnagar, 

 3500 feet {G. S. West), Croaghmore, Clare Island, 1520 

 feet, and at about the same elevation in N. "Wales and 

 N. Yorkshire. 



Eng[;And. — Cumberland, Westmorland, and Lanca- 

 shire (Brovm) ; N. and W. Yorkshire ; Derbyshire 

 (Broiun); Shropshire; Bedfordshire; Cambridgeshire; 

 Essex (Scourfield) ; Buckinghamshire ; Oxfordshire ; 

 Surrey {Broiim) ; Hampshire ; Isle of Wight. 



Wales. — Moel Siabod and Capel Curig, Carnarvon- 

 shire {llu'plc) ; Towyn, Merionethshire (Gash). 



Scotland. — Shetlands ; Orkneys, Ross-shire, and 

 Hebrides (West) ; Loch Ness {Penan]), Inverness-shire 

 {West, Broivn) ; Elginshire {Broivn); Aberdeenshire 



