LECYTHIUM SPINOSUM. 113 



long and fine, sometimes waving almost like flagellse, 

 twisted and knotted when withdrawn towards the 

 mouth. Test with irregular outline." 



The English individuals above described are very 

 similar to those from Switzerland figured by Penard 

 (1890) as Trinema spinosum which are considered by 

 Lauterborn to be distinct from his Pampliagus armatus ; 

 but, considering the flexibility of the envelope in this 

 genus, the variation in form is not more than frequently 

 occurs in other species of the genus, and the possession 

 of spines on a membranous test is of such rare occur- 

 rence that unless further differences are found to exist 

 it seems inadvisable to consider these un symmetrical 

 tests as even varieties. Indeed there can really be no 

 doubt as to the identity of this species with Penard's 

 Trinema spinosum ; and his specific name is therefore 

 retained although he appears to have accepted that of 

 Lauterborn. 



. Genus 42. PSEUDODIFFLUGIA Schlumberger, 



1845. 



Pseudodifflugia SCHLUMBERGER in Ann. Sci. nat. (3) III 



(1845), p. 256. 

 Pleurophrys CLAPAREDE & LACHMANN Etudes Inf. et Rhiz. 



I, 2 (1859), p. 454. 

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



(1872), p. 264. 

 Plagiophrys PENARD in Mem. Soc. Geneve XXXI, i, u 



(1890), p. 173. 



Test ovoid, chitinous, usually rigid, covered with 

 extraneous particles; transverse section circular or 

 elliptical; aperture terminal; plasma grey or colourless, 

 granular ; nucleus single, placed posteriorly ; a single 

 contractile vesicle usually present ; pseudopodia filose, 

 long, straight or branched, not anastomosing. 



This genus is closely allied to Lecythium, but is 

 distinguished by a more rigid envelope covered with 

 extraneous particles. In the species P. horrida and 



VOL. ii r. 8 



