214 BRITISH DESMID1A< I! i;. 



S. Pleurotaenium Hutchinsonii (Turn.) West & Gl. S. 



West. 



(PI. XXXI, fig. 7.) 



Dociiliinn Hutchinsonii Turn. Desni. Notes, IS'.CJ, p. :il.(i, iii;-. 16. 

 Pleurot&nium Hutchinsonii (Turn.) West & G. S. West, Alya-11. Yurks. 

 1900, p. 59. 



Cells somewhat small, 1112 times longer than their 

 diameter; semicells with a slight basal inflation, very 

 slightly attenuated to the apices; lateral margins 

 faintly sinuate, apices truncate with broadly rounded 

 angles; cell-wall covered with small papillae (2*5-3 /m 

 in length; those at the apices 1'7-2/x in length). 



Zygospore unknown. 



Length 245-280 /A; breadth at base of semicells 

 21-26 jit; breadth of apices 17-UK)^. 



ENGLAND. Strensall Common, N. Yorks. (W. II. 

 Turner). 



9. Pleurotaenium nodosum (Bail.) Lund. 

 (PL XXXI, figs. 3-6.) 



Closterium nodosum Bailey, 1846. 



Doi-iilinni nodosum Bail, in Ealfs' Brit. Desm. 1848, p. 218, t. 35, f. 8 ; 

 Bail. Microscop. observ. 1851, t. 1, f. 4; Arch, in Pritcli. Infus. isiil, 

 p. 745; Kabenh. Flor. Europ. Algar. Ill, 1808, p. 145 ; Arch, in Quart. 

 Journ. Micr. Sci. 1872, p. 193 ("forma"); Wolle, Desm. U.S. 1884, 

 p. 50, t. 11, f. 11, 12 ; t. 12, f. 20; Cooku, Brit. Desm. 18815, p. 12, t. 7, 

 t'. 2; Borge, Austral. Siisswasserchlor. 18915, p. 27, t. 4, f. 49-51. 



Pleiu-otaenium nodosum (Bail.) Lund. Desm. Siu-c. 1871, p. 90; Nordst. 

 Al--. Brasil. 1877, p. 17; Freshw. Ali>\ N. Zeal. 1888, p. 05; Johnson, 

 l.'are Desm. U.S. II, 1894, p. 290 ; West & G. S. West, Some N. AIIHT. 

 Desm. 1896, p. 234; Some Desm. U.S. 1898, p. 285; Freshw. Al--. 

 Ceylon, 1902, p. 141. 



Docidium nodosum var. llil'i-ii<<-n>n Cookc, I!rit. Desm. 1880, p. 13. 



Docidiupsis nodosa Eacib. Desni. Nowe, 1889, p. 107, t. 7, f. 22. 



D. nodosum a. typica Turn. Freshw. Aly. E. India, 1893, p. 35. 



D. Hoiltixinu y. dentatum Turn. 1. c. 



Cells large or moderately large, 6^8 times longer 

 than their diameter ; semicells with nodulose margins, 

 caused by four rings of prominent nodules, one basal 

 ring, and three other equidistant rings, 6-8 nodules in 

 each ring, gradually tapering from base to apex ; 

 apices dilated, convexo-truncate, furnished with a 



