PLEniOTJENITTM. 205 



Var. granulatum West. (PI. XXIX, figs. 7, 8.) 



Pica rnl:i'ni inn I rn nfii! ii 111 \-;\r. lira iniliil ii in West, New Brit. Fresliw. Al.y. 

 1S94, p. :< ; Roy & Biss. Scott. Desm. is<i|, p. I'|L'. 



A variety with the cell-wall distinctly and irregularly 

 granulate. 



Length 405-405 /x ; max. breadth 54-67 /A. 

 ENGLAND. Borrowdale, Cumberland ! 

 SCOTLAND. Ben Laoigli, Perth ! 



Var. Farquharsonii (Roy & Biss.) n<>l>. (PI. XXIX, 



figs. 5, 0.) 



Docidimn Farquharsonii Hoy, Freshw. Alg. Enbridge Lake and Vicin. 

 1890, p. 3:^5 ; Roy & Hiss. Scott, Desm. 1894, p. 241, t. 4, f. 1. 



This variety differs only from the typical form in 

 the somewhat sudden attenuation of the semicells near 

 the apex; apical tubercles large and very depressed, 

 12-14 in number (7 or 8 visible across the apex). 



Length 288-384 /A ; max. breadth 48-53 /A; breadth 

 at apices 22'5-28/x. 



ENGLAND.-- -Ball Hill Pond, Hants (Roy). Near 

 Land's End, Cornwall! 



SCOTLAND. Near Springhill, Aberdeen; Muchalls, 

 Kincardine ; Balquhadly Hill in Fern, Forfar ; Tent's 

 Moor, Fife ; Sheriffmuir near Dunblane, and Bracklin 

 near Callander, Perth (Roy <J* 



4. Pleurotaenium Ehrenbergii (Breb.) De Bary. 

 (PI. XXIX, figs. 9-11 ; PI. XXX, fig. 1.) 



Closterium Trabccula Ehrenb., 1830 [in part]. 



Docidimn Ehr?i<>'<',-iiii Breb. in Diet. univ. hist. nat. 1844, p. ! ; Knit's. 



Brit, Desm. 1848, p. 157, t. 26, f. 4 ; Arch, in Pritch. Infus. IStil, p. 7 i:.. 



t, 2, f. 8-11 ; t. 3, f. 46, 47 ; Cooko, Brit. Desm. 1886, p. 14, t. 6, f. 1 a, 



b, d -, West, Al-. N. Wales, 1890, p. 284 ; Eoy & Biss. Scott. Desm. 



is'. I1-, p. 241 (in part?). 



Penium (Docidium) Ehr,'nl><-,-(iii Kiitz. Spec. Alt;'. 1849, p. 168. 

 Pleurotwnium Ehrenlerrjii (Breb.) De Bary, Conj. 1858, p. 7o ; Hansg. 



Proilr. Alo-enfl. Bohm. 1888, p. 189; De Toni, Syll. Al--. ISS'.i, p. S'.u; : 



West, Alt;-. W. Ireland, 18!I2, p. ]!!: Al--. En<?. Lake Distr. ls.i2. 



p. 710; Nordst. Index Desm. 189(>, p. 114; West & G. S. West, A1 M -. 



S. England, 1897, p. 483; G. S. West, Al^a-fl. Cambr. 1S99. ]>. 11:!: 



