COSMARIUM. 113 



This variety is nearer var. subturgidum than the typical 

 form. It is characterized by its shorter semicells, its rounded 

 apical angles, and its delicately variolated cell-wall. 



121. Cosmarium viride (Corda) Josh. 

 (PI. LXXIY, figs. 16-18.) 



Colpopelta viridis Corda in Aim. de Carlsbad, 1834, pp. 179, 206, t. 2, 



f. 28 ; 1839, p. 241. 

 Cosmarium Cordanum Breb. in Rabenli. Flor. Europ. Alg. III, 1808, 



p. 177 ; Turner, New and Rare Desm. 1885, p. 934, t. 15, f . 4 [figure 



bad] ; West, Desm. Mass. 1889, p. 18, t. 3, f. 23 ; Borge, Siissw. Chlor. 



Archang. 1894, p. 23. 



C. viride (Corda) Joshua, New and Rare Desm. 1885, p. 34, t. 254, f. 3 ; 

 Johnson, Rare Desm. U. S. II, 1895, p. 292 ; West & G. S. West, Alg. 

 Madag. 1895, p. 71, t. 9, f. 27; Nordst. Index Desm. 1896, p. 271 ; West 

 & Gr. S. West, Some Desm. U. S. 1898, p. 311. 



Calocylindrus Cordanus Wolle, Freshw. Alg. U. S. 1887, p. 27, t. 60, f. 28. 

 DyspJiinctium Cordanum Hansg. Prodr. Algenfl. Bohm. 1888, p. 186. 



D. viride De Toni, Syll. Alg. 1889, p. 885 ; Turner, Freshw. Alg. E. India, 

 1893, p. 40. 



Cells somewhat small, about If times longer than 

 broad, moderately constricted, sinus a very obtuse- 

 angled depression ; semicells obovate-circular, widest 

 part about one-third from the apex, apices commonly 

 very slightly depressed. Vertical view circular. Cell- 

 wall punctate. Chloroplasts axile, one in each semi- 

 cell, with a central pyrenoid. 



Zygospore unknown. 



Length 41-55 /x; breadth 20-33 /x; breadth of 

 isthmus 14-22 /x. 



ENGLAND.- -Ennerdale, Cumberland ! 



IRELAND.- -Lakes between Clifden and Roundstone, 

 Galway ! 



Geogr. Distribution.- -France. Germany. Bohemia. 

 India. Madagascar. United States. Nova Scotia. 



C. viride is a very rare species which is distinguished from 

 C. moniliforme by the broader isthmus and the somewhat 

 different form of the semicells, as well as by its punctate 

 cell-wall. 



Forma minor West, (PI. LXXIV, fig. 19.) 



C. viride forma minor West, Alg-. W. Ireland, 1892, p. 161. 



Length 31-32'5/x; breadth 18-19 /x,; breadth of 

 isthmus 12 '5-1 5 /u. 



VOL. ni. 8 



