COSMAEIUM. 



Lake Distr. 1892, p. 729, t. 9, f. 16 ; Xordst. Index Desmid. 1896, p. 2<>7 : 



West &. G. S. West, Alg. S. England, 1897, p. 491 ; Alga-fl. Yovks. 1'. no. 



p. 87 ; Alo-. X. Ireland, 1902, p. 41 ; Freshw. Alg. Orkneys & Sht'tlands 



1905, p. 22. 

 Calocylindrus pseudarctous Cooke, Brit. Desm. 1887, p. 129, t. 44, f . 6 



West, Add. Alg. W. Yorks, 1889, p. 92. 

 Dysphinctium pseudarctoum De Toni, Syll. Alg. 1889, p. 879. 



Cells very small, about 1J times as long as broad, 

 very slightly constricted, sinus a very shallow depres- 

 sion; semicells widely subovate, apex often subtruncate. 

 Side view of semicell semi-elliptic with a slightly 

 narrowed base. Vertical view subcircular or circular- 

 elliptic. Cell-wall smooth. Chloroplasts axile, one 

 in each semicell, with a central pyrenoicl and four 

 radiating cruciately-disposed lobes (often very irre- 

 gular and most obscure). 



Zygospore subglobose or angular-globose, smooth. 



Length 1(3-3-24 p.; breadth" 11 '2-18 ^ ; breadth of 

 isthmus 10-16*8 ^ ; thickness 10*5 14'5 /x, ; cliam. 

 zygosp. 14'4-lS p.. 



EXGLAXD.- -Wastdale, Cumberland ! Pike of Bliscoe, 

 Louoiirio'o- and Helvellvn, Westmoreland ! Hawks- 



OO ' 



head, Lanes. ! Ogden Clough, Eombald's Moor, and 

 Cautley Spout, WT Yorks ! Carlton Bank, K Yorks ! 

 Esher West-end Common, Surrev ! 



* 



WALES. Capel Curig, Llyn Idwal, Llyn Ogwen, 

 Llyn-y-cwm-ffynon, and Llyn Greirionedd, Carnarvon- 

 shire ! 



SCOTLAND.- -Clova Mts., Forfar ! Skye in Inverness ! 

 Orkneys ! Shetlands ! 



IKELAXD.- -Errigal, Donegal ! Ballynahinch, Gralway ! 

 Carrantuohill and near Lough Brin, Kerry ! Slieve 

 Donard, Down ! Lough Fea, Londonderry ! 



Geoar. Dixtribnfion. Xorwav. Grreenland. Switzer- 



" . 

 land. Siam. 



We sometimes meet with this minute species in abundance 

 in upland and subalpiiie localities, often amongst mosses 011 

 wet rocks, and more rarely amongst submerged Sphagnum 

 and Hypninn in peaty areas. The zygospores we have only 

 seen from wet rocks on the Gornergrat at 8500 ft. 



C. pseudarctoum differs from C. arctoum in the upward 

 VOL. III. 3 



