62 BRITISH FRESHWATER RHIZOPODA. 



Pontigulasia, is that of the commoner forms of Difflugia 

 oblonga Ehrenb. 



3. Pontigulasia compressa (Carter). 

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



Difflngia compressa CARTER in Ann. Nat. Hist. (3) XIII 

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

 Ill (1867), p. 66. 



Difflngia pyriformis var. vas sub-var. bigibbosa PENARD in 

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



Pontigulasia bigibbosa PENARD Faune Rhiz. Leman. (1902), 

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

 f. ; and in 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 (1905), 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 1 30-1 50 /x, ; breadth about 

 100 //,. Penard records examples from Lake Leman 

 250 /t in length. 



In wet Sphagnum, in boggy places, also in the 

 deep water of lakes. Dunham, Cheshire, 1904; 



