AVERINTZIA. 65 
Test similar to that of Heleopera but having a small 
elliptical aperture. 
The walls of the. test around the aperture are 
considerably thickened but taper very gradually to 
normal. This portion of the test is quite characteristic 
and at once distinguishes it from the test of any species 
of Heleopera, the only genus with which it is likely to 
be confused. 
This genus contains only one species, A. cyclostoma 
(Heleopera cyclostoma Penard). No characteristics of 
the genus are given by its author: 
1. Averintzia cyclostoma {Penard) Schouteden. 
(Plate LXII, figs. 12 and 13.) 
Heleopera cyclostoma 
PENARD Faune Rhiz. Leman (1902), pp. 390-393, 6 figs. 
Awerinzewia cyclostoma 
ScHOUTEDEN in Ann. Biol. lacustre, I, 3 (1906), p . 357. 
PENARD in Brit. Antarctic Exped. 1967-9, I, 6 (1911), p . 225. 
Waites & PrENaARD in Proc. R. Irish ‘Acad. XX¥L Lxv (1911), 
p. 9, 15, 22. 
Wosunes | in Jn. Linn. Soc., Zool. XXXII (1912), pp. 125, 143, 156; 
(1913), pp. 211, 218. 
HEInIs in Mém. Soc. Neuchatel, V (1914), pp. 677, 680, 693, 696. 
EDMONDSON in Ward & Whipple's Fresh-water Biology (1918), 
p. 227, £. 317. 
_ Test of moderate size, broadly ovoid, compressed, 
composed of various- sized quartz-grains cemented in 
a chitinous material of a dark violet colour; surface 
of test smooth except at the crown where. a few 
adherent grains may occasionally be present; test in 
narrow side view elongate-oval; transverse section 
elliptical ; aperture small, terminal, elliptical, bordered 
internally by a thickening of the walls of the test; 
nucleus single, large, granular; pseudopodia not 
observed. 
‘Length 135-180 y»; breadth about three-quarters 
‘the length; thickness three-fifths to two-thirds the 
‘breadth ; nucleus 33 dia. (Penard). . 
Habitat.—Sphagnum and aquatic vegetation. 
VOL. IV. 5 
