BUASTRUM. 



Kincardine, Perth ! Argyll, Arran (Roy $* Bissett). 

 Ross and Skye ! General and often abundant in the 

 Outer Hebrides ! 



IRELAND. Louo-h Macsrath and near Duno-loe, 



O O O 



Donegal ! Xear Foxford, Mayo ! Ballvnahinch, Kyle- 



II V I/ 



more, and Lakes near Recess, Gahvay ! Carrantuohill 



' V 



and near Castletown, Kerry! Dublin and Wicklow 

 (Archer). 



Geogr. Distribution. Sweden. India (var.). United 

 States. 



This characteristic species is somewhat rare in the British 

 Islands. In some parts of the west of Ireland, Skye, and 

 in the Outer Hebrides, it occurs in large quantity along with 

 E. inerme (Halt's) Lund. 



It is considerably smaller than E. crassum, of different pro- 

 portions, and differs considerably in its lateral lobes, the 

 upper lobules of which are entire. "\Volle observed the zygo- 

 spore from Florida, U.S.A. 



2. Euastrum crassum (Breb.) Ktitz. 

 (PL XXXIII, figs. 4-6.) 



Heterocarpella crassa Breb. in Cheval. microscop. et usage, Paris, 1839, 



p. 272 (name). 



Cosmarium crassum Breb. in Meuegh. Synops. Desm. 1840, p. 222. 

 Euastrum Pelta Ralfs in Ann. Mag. Xat. Hist,, xiv, 1844, p. 190, t. 7, f. 1. 

 Euastrum crassum (Breb) Ktitz. Phycol. germ. 1845, p. 135; Ealfs, Brit, 



Desm. 1848, p. 81, t. 11, f. 3 ; Arch, in Pritcli. Infus., 1861, p. 728 ; 



Eabenh. Flor. Europ. Algar. Ill, 1868, p. 181 ; Liind. Desm. Suec. 1871, 



p. 17, t. 1, f. 10 ; Kirchn. Alg. Schles. 1878, p. 157 ; Wolle, Desm. U.S., 



1884, p. 97, t. 25, f. 1-3 ; Cooke, Brit. Desm. 1886, p. 65, t. 32, f. 1 ; 



Hansg. Prodr. Algenfl. Bohni. 1888, p. 205 ; De Toni, Syll. Alg. 1889, 



p. 1088; West, Alg. X. Wales 1890, p. 287, t. 6, f. 33; West, Alg. 



W. Ireland, 1892, p. 136 ; Roy & Biss. Scott. Desm. 1893, p. 176; West 



& Li. S. West, Alg. S. England, 1897, p. 483 ; Alga-fl. Torks. 1900, p. 60 ; 



Alg. N. Ireland, 1902, p. 27. 



E. crassum var appendiculatum Breb. Liste Desm. 1856, p. 122. 

 E. crassum b. majus Rabenh. Flor. Europ. Algar. Ill, 1868, p. 182. 

 E. crasso-humerosum Benn. in Ann. Bot. iv, 1889, p. 171 ; in Journ. Eoy. 



Micr. Soc. 1890, p. 7, t, 1, f. 14 (figure bad ! ). 

 Helierella crassa Kuntze, Eevis. gen. plant. 1891, p. 898. 

 Euastrum magnificum Wolle var. crassoides Wolle, in Hastings' 'Desm. 



New Hampsh./ Amer. Month. Micr. Journ. 1892, p. 153, f. 1. (Vide 



West. & G. S. West in Journ. Bot. 1895, p. 67.) 



Cells large, almost twice as long as broad, elliptic- 

 oblong, deeply constricted, sinus narrowly linear ; 

 semicells in front view unequally three-lobed, inter- 



