(32 BRITISH FRESHWATER RHIZOPODA. 



PontigvJafiia, is that of the commoner forms of Diffluijia 

 ohlonga Bhrenb. 



3. Pontigulasia compressa (Carter). 

 (Plate XXIII, figs. 3-5 ; and fig. 72 in text.) 



Difflugia comfressa Carter in Ann. Nat. Hist. (3) XIII 



■(1864), p. 22, t. -i, ff. .5, 6; Parpitt in Tr. Devon Assoc. 



Ill (1867), p. 66. 

 Di.-fflugia pyriforiais var. vas sub-var. higihbosa Penard in 



Rev. Suisse Zool. VII, 1 (1899), p. 26, t. ii, f. 10. 

 Pontigulasia higibbosa Penard Paune Rhiz. Leman (1902), 



p. 322, ff. 1-3 (p. 323); Sarc. grands Lacs (1905), p. 35, 



f. ; nndin Pr. R. Soc. Edinb. XXV, 8 (1905), p. -595; 



ZsCHOKKE in Arch. Hydrobiol. II, I (1906), p. 4. 

 (Non Pontigulasia compressa Rhumbler in Zeits. wiss. Zool. 



LXI, 1 (i905), p. 105, t. iv, f. 13.) 



Test large, roundish pyriform, nearly as broad as 

 long, and unequally compressed ; the body, or upper 

 three-fourths (above the constriction) broadly reni- 

 form, its convex surface forming the crown of the 

 test, whilst the outline of the concavity — in empty 

 tests usually sharply defined, and coterminous with 

 the constriction — marks the junction with the neck, 

 which is more strongly compressed and is sub- 

 stantially less dense than the bi-gibbous lower surface 

 of the body. Sides of the neck tapering evenly down- 

 wards to the comparatively narrow truncated mouth, 

 of which the orifice is round or broadly elliptical in 

 outline. Body constructed of minute quartz-grains, 

 and rough on the surface ; the neck less so, and lighter 

 in colour. A doubly perforated diaphragm (figured 

 by Penard in ' Faune Rhiz. Leman ') crowning the test 

 internally at the point of constriction. Nucleus single ; 

 protoplasm and pseudopodia normal. 



Dimensions : Length 130-150 /i,; breadth about 

 100 jM. Penard records examples from Lake Leman 

 250 ju, in length. 



In wet Sphagnum, in boggy places, also in the 

 ■deep water of lakes. Dunham, Cheshire, 1904; 



