48 BRITISH FRESHWATER RHIZOPUDA. 
irregularly -serrated and surrounded by a four-lobed 
annular collar; plasma grey, granular, containing 
Zoochlorella-cells living in symbiotic relationship ; 
nucleus single, large ; one or more contractile vesicles 
usually present ; pseudopodia numerous, digitate. 
The genus contains only one species, the test of 
which in general appearance and characteristics 
resembles that of a Dvfflugia, but the collar around 
the aperture at once distinguishes it. 
There are in reality two apertures to the test, the 
outer one four-lobed and the inner and smaller one 
with irregular edges.- 
1. Cucurbitella mespiliformis Penard. 
(Plate LX, figs. 12 and 13.) 
Difflugia lobostoma 
Lerpy (pars) Freshw. Rhiz. N. Amer. (1879), p. LIA, pl. xv, £. 7. 
Cucurbitella mespiliformis 
PENARD in Rev. Suisse Zool. IX (1901), p. 287; Faune Rhiz. Léman 
(1902), pp. 311-314, 6 figs.; Sarcodinés in Cat. Invert. Suisse (1905), 
pp. 60-61. 
a aad in Trudui S.-Peterb. Obshch. XXXVI, 11 (1906), pp. 
176-17 
ScHOUTEDEN in Ann. Biol. lacustre, I, 3 (1906), p. 340. 
Wares in Jrn. Linn. Soc., Zool. XXXII (1912), pp. 124, 133; 
Naturalist, 1913, p. 146. 
Test ovoid, moderately large, dark grey in colour, 
composed of variously-shaped silicious grains and 
plates ; aperture terminal, small, irregularly serrated, 
surrounded by a three- or four-lobed annular collar ; 
plasma grey, granular, containing Zoochlorella-cells 
hving.in symbiotic relationship ; nucleus large, usually 
containing a large central nucleole which may occasion- 
ally be divided ; one or more contractile vesicles usually 
present ; pseudopodia numerous, short, digitate. 
Length 116-140 »; diameter 80-105 #3 inner 
aperture 15-16 » in diameter; outer aperture 23-33 
across the widest part; collar 43-50 / in diameter. 
Habitat.—The ooze of ponds and aquatic vegetation. 
Encianp.—Husthwaite near York. 
Ls 
