DIFFLUGIA OLLIFORMIS. 41 
covered with variously-shaped small silicious grains ; 
aperture large, circular, with a narrow collar; ‘plasma 
normal; pseudopodia few, long, digitate. 
Length 5U-84 »; breadth 44-80 yw; diameter of 
collar 30-50 pw. (Lagerheim—length 59-70 »; diameter 
44-68 p.) 
Habitat.— Aquatic vegetation. 
EncGuanp.—Pilmoor and Gormire, Yorkshire. 
Wares.—Bodelwyddan, N. Wales. 
Scortanp.—Orkney Islands; Outer Hebrides. 
In addition to tests of average size, a small variety 
occurs at Pilmoor, about 30 pw in length, similar to the 
small form illustrated by Lagerheim (figs. 4, 5). 
The test is very similar to that of D. subeequatis 
Penard, but is distinguished from it by the compara-~ 
tively smaller aperture which causes the length to be 
slightly greater than the breadth of the test; it is also 
much more variable in size. The dimensions of D. 
subequalis are, length 80-82 »; breadth about 88 yu 
(Penard, ‘ Revue Suisse de Zoologie,’ vol. xviii (1910), 
p- 938). 
Difflugia tuberculata var. minor Wailes. 
(Plate LXI, figs. 12 and 13.) 
Diflugia tuberculata var. minor 
Wal es in Jrn. Linn. Soc., Zool. XXXII (1912), p. 124. 
~ Test of medium size, pyriform, not compressed, 
composed of variously-sized quartz-grains with an 
occasional admixture of diatom-frustules; aperture 
small, approximately hexagonal, bordered by a pro- 
jecting lip; plasma and pseudopodia as in the type. 
Length 74-100 »; diameter 52-90 m; aperture 
23-25 p. 
Habitat.— Ponds and aquatic vegetation. 
Enguanp.—Windermere, Westmorland; Pilmoor, 
Yorkshire. 
The typical D. tuberculata is characterized by the 
