52 BRITISH FRESHWATER, RHIZOPODA. 



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



HOPKINSON in Irish Natur. 1910, p. 3. 



WAILES & PENAKD in Proc. R. Irish Acad. XXXI, LXV (1911), pp. 



15, 21-22. 

 WAILES in Scott. Natur. 1912, pp. 60. 62 ; in Jm. Linn. Soc., Zool. 



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

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

 Assulina semilunum 



PENARD in Mem. Soc. G-eneve, XXXI, 1, 11 (1890), pp. 175-176, pi. 



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



in Amer. Natur. XXY (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 ; 

 pseudppodia few, straight, divergent, slender, seldom 

 branched. 



Length usually 60-90 /x, but may attain 150/n; 

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

 two fifths of the breadth. 



Habitat. Sphagnum and mosses in marshy situations. 



Generally distributed in the British Isles. It is 

 found at considerable elevations, e. g. Lochnagar, 

 3500 feet (G. 8. West), Croaghmore, Clare Island, 1520 

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

 N. Yorkshire. 



ENGLAND. Cumberland, Westmorland, and Lanca- 

 shire (Brown) ; N. and "W. Yorkshire ; Derbyshire 

 (Brown}; Shropshire; Bedfordshire; Cambridgeshire; 

 Essex (Scourfield) ; Buckinghamshire ; Oxfordshire ; 

 Surrey (Brown) ; Hampshire ; Isle of Wight. 



WALES. Moel Siabod and Capel Curig, Carnarvon- 

 shire (Hoplc.) ; Towyn, Merionethshire (Cash). 



SCOTLAND. Sh'etlands; Orkneys, Ross-shire, and 

 Hebrides (West) ; Loch Ness (Penard), Inverness-shire 

 (West, 'Brown) ; Elginshire (Brown) ; Aberdeenshire 



