56 BRITISH FRESHWATER RHIZOPODA. 



moderate size, containing a single nucleole ; numerous 

 vacuoles usually present; pseudopodia filose, seldom 

 branched, straight, radiating, and few in number. 



Length 28-58 /A; breadth 19-50 /x; aperture 6-16 /A; 

 thickness one half to two thirds of the breadth ; scales 

 3-4 fj, in length. 



Habitat. Mosses and sphagnum. Common. 



Generally distributed in the British Isles and usually 

 numerous. 



Although empty tests are nearly everywhere nume- 

 rous, living animals are not very common, and active 

 individuals are rarely observed. In situations where 

 moss is liable to considerable desiccation, individuals 

 are few and their tests are often distorted ; a large 

 proportion of the empty tests are found with the two 

 sides pressed together ; this weakness may be due to 

 the lenticular shape of the tests in transverse section. 



The affinities of Euglypha denticulata Brown to this 

 species have already been referred to on p. 42. 



Genus 35. SPHENODEBJA Schlumberger, 1845. 



Sphenoderia SCHLUMBERGER in Ann. Sci. nat. (3) III (1845), 



p. 256. 

 Euglypha (pars) CARTER in Ann. Nat. Hist. (3) XV (1865), 



p. 290. 

 Difflugia (pars) EHRENBERG in Abh. Akad. Wiss. Berlin, 1871 



(1872), p. 264. 



Test globular or ovoid, hyaline, composed of 

 regularly-imbricated silicious plates or scales ; aper- 

 ture terminal, lipped, linear or circular; nucleus usually 

 large, placed posteriorly; plasma colourless, partly 

 filling the test ; one or two contractile vesicles usually 

 present; pseudopodia long, filose, delicate, straight or 

 forked. 



Four species of this genus are known, all of which 

 have been recorded in the British Isles. 8. dentata 



