Konua ScoticB, forma nov. (1*1. XXIX, iig. 1.) 



( 1 clls about 17 times longer than their diameter, 

 M-arcely attenuated; semicells with tlnve or four 

 smaller undulations above the basal inflation, the rest 

 of the lateral margins straight ; with a ring 1 of -^ 

 elongated tubercles round the apex (11 visible); cell- 

 wall minutely punctate. 



Length (i-)"J/x; breadth at base of semieells ; >7 /x, at 

 apex 158 fji. 



SCOTLAND. Rhiconich, Sutherland ! 



Forma Cambrica>///^' nov. (PL XXIX, fig. 



Cells about 14 times longer than their diameter, 

 'scarcely attenuated; semieells with a second large 

 inflation above the basal inflation, the rest of the 

 lateral margins straight; with a ring of 20 elongated 

 tubercles round the apex (11 visible); cell-wall minutely 

 punctate. 



Length 660 p ; breadth at base of semieells 47 IJL, at 

 apex 30 IJL. 



WALES. Capel Curig, Carnarvonshire ! 



3. Pleurotaenium truncatum (Breb.) X;ig. 

 (PI. XXIX, figs. 3, 4.) 



Clostcrium truncatum Breb. in Cheval. microscop. et leur usage, Paris, 



1839, p. 272 ; Breb. iu Menegh. Synops. Dcsm. 1S4O, p. 235. 

 Docidium tru /n-nt mtt Breb. in Kalfs' Brit. Desm. 1848, p. 15U, t. 2(i, f. 2; 



Arch, in 1'ritch. Infus. 1861, p. 745 ; Cooke, Brit. Desm. LSMi, p. 15, 



1. G, f . -1 ; Koy & Biss. Scott. Desm. 1894, p. 242. 

 1'i.inn-iit u' ilium '' t rn m'xt inn (Breb.) Nag-, tratt. einz. Alg. 1849, p. !(>! ; De 



Bary, Conj. 1858, p. 75 ; Eabenh. Flor. Europ. Algar. Ill, IMS, p. 142; 



Delp. Desm. subalp. 1877, p. 127, t. 19, f. 7-11 ; Hansg. Prodr. Al^cntl. 



Bohin. 18SS, p. 1'JU; De Toni, Syll. Alg. LSS9, p. Wi7 ; West. Alg. W. 



Ireland, 1892, p. 119; Liitkem. Desm. Attersees, 1893, p. 54(5; "West \- 



G. S. West, Alg. S. England, 1897, p. 483 ; Alga-fl. Yorks. 1901), p. 59. 



Cells large, (3-8 (rarely up to 10^) times longer than 

 their diameter ; semieells somewhat tumid, generally a 

 little broader in the middle than at the base, gradually 



