COSMARIUM. 167 



Portianum (vide PL LXXX, fig. 8) belongs undoubtedly to 

 some other species. It is also questionable whether the 

 smooth zygospore figured by Reinsch of " C. pseudomargariti- 

 ferum " (vide PI. LXXX, fig. 9) should be regarded as that of 

 C. Portianum, notwithstanding Archer's expressed opinion 

 that Keinsch's species was identical with his C. Portianum. 

 If this be the case., then the zygospore figured by Reinsch is 

 immature, not having as yet developed the conical warts. 



The tropical forms of this species are considerably smaller 

 than those occurring in temperate regions. [Length 20-25 /n \ 

 breadth 14*5-19^; breadth of isthmus 5-8'5/x; thickness 

 10-12-5 



Var. nephroideum Wittr. (PI. LXXX, figs. 10, 11.) 



C. Portianum Arch. var. nephroideum Wittr. Gotl. ()1. sotv. Alg. 1872, 



p. 57 ; Nordst. Bornh. Desm. 1888, p. 193, t. 6, f. 15 ; Heimerl, Desm. 



alpin. 1891, p. 596 ; Gtitw. Flor. glonow Galic. 1892, p. 129 ; West, Alg. 



W. Ireland, 1892, p. 153 ; Liitkem. Desm. Central China, 1900, p. 119 ; 



West & GK S. West, Alg. X. Ireland, 1902, p. 38. 



? C. armillatum Turner, Freshw. Alg. E. India, 1893, p. 55, t. 8, f. 22. 

 C. nephroideum (Wittr.) Roy & Biss. Scott. Desm. 1894, p. 169, t. 2, f. 3. 



Usually smaller than the type ; semicells subreni- 

 form or semicircular-elliptic. 



Length 25-31 /i; breadth 22-27 ju; breadth of 

 isthmus 7-10 /n ; thickness 1216 /n. 



SCOTLAND.- -Glen Clunie near Braemar, Aberdeen; 

 Arran (Eoij $ Bissett). 



IRELAND. Dunoloe, Lousrhs Cloncarney and Darragh, 



o o / o 



and near Lough Magrath, Donegal ! Lakes east of 

 Lousfh Bonn, Galway ! 



O t> 



G-eogr. Distribution.- -Germany. Austria and Galicia. 

 Sweden. Faeroes. Iceland. Central China. 



This variety is distinguished by the form of its semicells, 

 which are considerably flattened at the ventral margin. The 

 granules are rather smaller than in the type,, but they have a 

 similar disposition in vertical series. 



160. Cosmarium orthostichum Lund. 

 (PL LXXX, figs. 12-19.) 



Cosmarium orthostichum Lnnd. Desm. Suec. 1871, p. 24. t. 2, f . 9 : Wolle, 

 Desm. U. S. 1884, p. 78, t, 18, f. 4-5 ; Cooke, Brit. Desm. 1887, p. 105, 

 t, 42, f . 3 ; De Toni, Syll. Alg. 1889, p. 963 ; West, Alg. N". Wales, 1890, 



