116 BRITISH FRESHWATER RHIZOPODA. 



PENARD in Mem. Soc. Geneve, XXXI, i, n (1890), p. 170, pi. vii, ff. 

 115-117 ; pi. viii, ff. 1-7 ; in Jahrb. nassau. Ver. Naturk. XLIII 

 (1890), p. 71. 



RHUMBLER in Zeits. wiss. Zool. LXI (1895), p. 95. 

 DELAGE & HEROUARD Traite Zool. concrete, I (1896), p. 115. f. 151. 

 Plagiophrys gracilis 



PENARD in Mem. Soc. Geneve, XXXI, i, n (1890), p. 173, pi. viii, 



ff. 43-45 ; in Rev. Suisse Zool. VII (1899), p. 60, pi. vii, f. 37. 

 THIEBAUD & FAVKE in Ann. Biol. lacustre, I (1906), pp. 68, 76. 

 Pseudodifflugia hemisphaerica 



PENARD in Arner. Natur. XXY (1891), p. 1083. 

 Difflugia urceolata 



FRANCE (pars) in Res. Erforsch. Balatons. II, i (1897), p. 7. 



Test light brown or yellowish in colour, broadly 

 ovoid or sub-spherical; covered with fine quartz-grains ; 

 not compressed; aperture circular, terminal, devoid 

 of neck; nucleus placed posteriorly; a small contractile 

 vesicle sometimes discernible; pseudopodia long, filose, 

 straight or forked. 



Length 30-55 p. ; aperture 10-20 /u,. 



Habitat. Aquatic vegetation. 



ENGLAND. N. Yorkshire ; Cheshire (Cash) ; Shrop- 

 shire ; Bedfordshire ; Essex (Scour field) ; Bucking- 

 hamshire ; Isle of Wight ; Devonshire ; Cornwall. 



WALES.T Llyn Bochlwyd and Capel Curig, Carnar- 

 von shire ( West} . 



SCOTLAND. Shetlands; Outer Hebrides; Inverness- 

 shire (Brown). 



IRELAND. Clare Island, Mayo ; Wicklow (Archer). 



Between the limits of length (20-65 /A) indicated by 

 Penard are a number of forms which show~ considerable 

 variation in colour, relative size of aperture, and the 

 character of the adherent foreign particles as well as 

 in the appearance of the pseudopodia. The larger 

 sub-spherical forms appear to be rare in the British 

 Isles, the type usually found being broadly ovoid and 

 of rather small size (30-40 //, in length). 



This species is distinguished from P. fulva by its 

 larger size and the usually comparatively smooth ex- 

 terior of its test; the character of the pseudopodia and 

 colour of the test distinguish it from species belonging 

 to the genera Difflngia and Pliryganella. 



