TRINEMA ENCHELYS. 91 



It is doubtful whether Ehrenberg, when describing 

 the species which he first called Difflitgia enchelus, had 

 before him Trinema enchelus or T. lineare, or indivi- 

 duals of both these species. Subsequently, however, 

 when he came to the conclusion that they were dis- 

 tinct species, and Arcellse, not Diffluc/ide, he confined 

 the name enchelys to the larger form, and called 

 the smaller one Arcella enchelys (hyalina) or only A. 

 hi/alina. Subsequent writers again confused them, 

 and probably many records given in the synonymy 

 under T. enchelys pertain to T. lineare. Penard first 

 clearly defined the two species. 



Var. galeata Penard. (PI. XLVIII, figs. 1-3.) 



Trinema enchelys var. galeata 

 PENARD in Mem. Soc. Geneve XXXI, i, n (1890), p. 186, pi. x, ff. 61, 



63-66 ; Faune Rhiz. Leman (1902), p. 528 and note, ff. 5, 6. 

 BROWN in Scott. Natur. 1912, p. 112 ; 1913, p. 110. 

 WAILES in Jm. Linn. Soc., Zool. XXXII (1913), pp. 208, 213. 



Test similar to that of the type but the anterior 

 portion of the orifice furnished with a wide border; 

 the nucleus usually containing two or three nucleoles ; 

 plasma and pseudopodia normal. 



Length 40-60 p ; breadth 20-40 p. 



Habitat. Mosses. 



This variety is not uncommon, being frequently 

 found in association with the type in the drier mosses. 

 It is generally distributed in the British Isles. 



It much resembles T. complanatum but is distin- 

 guished by the presence of usually well-defined lines, 

 visible in the ventral view, indicating where the wide 

 border of the aperture joins the body of the test. 



2. Trinema lineare Penard. 

 (Plate XL VII, figs. 11-21, and fig. 153 in text.) 



Difflugia enchelys 



EHRENBERG (pars) Infusionsth. (1838), p. 132. 



PRITCHARD (pars) Hist. Infus. (1842), p. 168; ed. 2 (1845), p. 168; 

 ed. 3 (1852), p. 206 ; ed. 4 (1861), p. 553. 



