AVEBINTZIA. 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. 1907-9, 1, 6 (1911), p. 225. 

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



pp. 9, 15, 22. 

 WAILES in Jrn. Linn. Soc., Zool. XXXII (1912), pp. 125, 143, 156; 



(1913), pp. 211, 213. 



HEINIS in Mem. Soc. Neuchatel, Y (1914), pp. 677, 680, 693, 696. 

 EDMONDSON in Ward & Whipple's Fresh-water Biology (1918), 

 p. 227, f. 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 /x; breadth about three-quarters 

 the length ; thickness three-fifths to two-thirds the 

 breadth; nucleus 33 /A dia. (Penard). , 



Habitat. Sphagnum and aquatic vegetation. 



VOL. iv. 5 



