CLOSTERIUM. 117 



Cooke, Brit. Desm. 1886, p. 17, t. 8, f. 2 b and (7 Hansg. Pnlr. Algonfl. 

 Bohm. 1888, p. 17!); Hanptfl. Zellm. u. Hiillgallerte Desin. isss, p. 99, 

 t. 3, f . 29 and 37 ; West, Alg. N. Wales, 1890, p. 284; Hoimerl, Dc.-.m 

 Alp. 1891, p. 592; West, Alg. W. Ireland, 1892, p. 120; Johnson, K.-M-K 

 Desni. U.S. I, 1894, p. 286; Eoy & Biss. Scott. Desm. 1891, p. 211 : 

 Nordst. Index Desm. 1896, p. 107; West & G. S. West, Alg. S. England, 

 1897, p. 479 ; Alga-fl. Yorks. 19m, p. 53 ; Alg. N. Ireland, 1902, p. 22. 



Cl. subrcctum Breb. Alg. Falaise, 1835, p. 59, t. 8. 



Cl. Baillyanum Breb. in Jcnner's Flor. Tunbridge Wells, 1845, p. xix. 



Cl. Ensis Focke, Phys. Stud. I, 1847, p. 59, t. 3, f. 31. 



Cl. didymotocum var. Baillyanum Breb. in Ealfs' Brit. Desm. 1848, p. Ki'.t. 

 t. 28, f. 7 c and d; Eabenh. Flor. Europ. Algar. Ill, 186s, p. 125; 

 Cooke, Brit. Desm. 1886, t. 8, f . 2 a, c, c. ; Hansg. Prodr. Algenfl. Bohm. 

 1888, p. 179. 



Cl. antiacerosum De Not. Desm. Ital. 1867, p. 61, t. 6, f. 63 ; Nordst. 

 Norges Desm. 1873, p. 41 ; Eoy & Biss. Scott. Desm. 1894, p. 243. 



Arthrodia didymotoca Kuntze Eevis. gen. plant. 1891, p. 883. 



Closterium fractum Turn. Freshw. Alg. E. India, 1893, p. 20. 



Cells large, 9-12 times longer than their diameter, 

 slightly curved, outer margin from 27 to 32 of arc, 

 inner margin very slightly concave or almost straight, 

 median portion of cell with subparallel sides, gradu- 

 ally and slightly attenuated towards the apices, which 

 are broad and truncate with rounded angles (and 

 sometimes very slightly recurved) ; cell-wall reddish- 

 brown or yellow-brown in colour, smooth or very 

 rarely with traces of a fine striation, with an annular 

 thickening of a dark brown colour at each apex ; 

 each chloroplast with 5-7 large pyrenoids ; terminal 

 vacuoles with many moving granules. 



Zygospore unknown. 



Distance between apices (= length) 295-672 ju ; 

 breadth 24-48 /A; breadth of apices 13-20 jot. 



ENGLAND. Westmoreland! (Ralfx; Bisseff). W. 

 Yorks! Lancashire! Cumberland! Warwick (Witts). 

 Sussex (Ralfs). Surrey! (Ealfs). Hants! (Ealfs). 

 Devon! Cornwall! (Ealfs). 



WALES. General in Carnarvonshire (at 2,200 ft. on 

 Grlyder Facli) ! Dolgelly, Merioneth ! 



SCOTLAND. General ! (Eoy fy Bissett). General in 

 the Outer Hebrides ! 



IRELAND. Mayo ! Galway ! Kerry ! Donegal ! 

 Dublin and Wicklow (Archer). 



Geogr. Distribution. -France. Germany. Austria. 



