COSMARIO1. 177 



IEELAXD. Donegal ! Mavo ! Galwav ! Kerry ! 



V / / 



Down ! 



Geof/r. Distribution. Switzerland. Italy. Portugal. 



-' / O 



Sweden. Greenland. United States. Brazil. 



C. sphalerostichum is largely an alpine Desmid, occurring 

 more frequently on dripping rocks and in small bog'gy moun- 

 tain streams than in other situations. It is not infrequent in 

 the mountainous areas of the British Islands, and it also 

 occurs on some of the old heaths. It stands perhaps nearest 

 to C. orthostichum yar. pumilum, but is distinguished by its 

 smooth apices, its acute lateral granules, and by the much 

 greater irregularity in the general granulation. 



168. Cosmarium geminatum Lund. 

 (PL LXXXI, fig. 15.) 



Cosmarium geminatum Lund. Desm. Suec. 1871, p. 31, t. 6, f . S : Wille. 

 Sydamerik. Algfl. 1884, p. 15 ; De Toni, Syll. Alg. 18S9, p. 992 : 

 Eicliler in Pamietnik Fizyj. Warsza^v. x, 1890, p. 87 : Xordst. Index 

 Desm. 1896, p. 128. 



Ursinella geminata Kuntze, Eevis. gen. plant. 1891, p. 924. 



Cells small, as long as broad, very deeply constricted, 

 sinus acute-angled and slightly open ; semicells oblong 

 and truncately rounded at each lateral extremity, apex 

 very widely subtruncate, ventral margin subconvex, 

 delicately granulate-dentate all round the external 

 margin, also granulate within the margin, in the centre 

 witli a pair of very small quadrifid (4-granulate) 

 tumours transversely disposed. Side view of semicell 

 circular-hexagonal, apex truncate, and on each side 

 with two denticulations and a median emarginate wart. 

 Vertical view elliptic in outline, at and near the poles 

 sinuate-denticulate, with a pair of small emarginate 

 warts at the middle on each side, and with two series 

 of granules within the margin ; in the centre smooth. 



Zygospore unknown. 



Length 18-27 /u; breadth 20-28 /u; breadth of isth- 

 mus 8-8* 7 /*; thickness 12-17'5/u. 



WALES.- -Capel Curig, Carnarvonshire! 



Geogr. Distribution.- -Germany. Gralicia in Austria. 

 Poland. Sweden. Central China (var.). Japan. Brazil. 



VOL. III. 12 



