COSMARIUM. 11 



the cell-wall being thickened at the base of the 

 incisions. 



Length 25-38 /u ; breadth 20-25 .,< ; breadth of 

 isthmus o-8'Oju; thickness 11-16^. 



ENGLAND. Kirk Fell, Cumberland ! Near Stickle 

 Tarn, Westmoreland ! 



"\VALES.- -Llyn-y-cwm-ffynon, Carnarvonshire ! 



IRELAND. Ballynahinch and Athiy Lough, Gal way ! 



Geogr. Distribution. Australia. 



The sides of the semicells of this variety are tricrenate, 

 and at the hase of each of the incisions the cell-wall is 

 thickened. This is best seen when the cell is slightly oblique. 

 The form described from the West of Ireland as "forma 

 incrassata" differs only in size and is therefore included in 



V 



the description of var. hypoJiewagonum. Borge has suggested 

 (in ' Xuova Notarisia/ 1894,, p. 21) that this variety does not 

 belong- to C. venustum, but we think it much too near that 

 species to be separated from it. 



Var. majus Wittr. (PI. XCII, fig. 2.) 



Euastrum venustum var. majus Wittr. Skandinav. Desni. 1869, p. 7, t. 1. 



f. 1. 

 Cosmariv.m venustum var. majus Wittr.; Roy. & Biss. Scott. Desm. 1894, 



p. 77 ; West, Alg. S. England, 1897, p. 487 ; West & GK S. West, Alg. 



N. Ireland, 1902, p. 35; Freshw. Alg. Orkneys and Slietlands, 1905, 



p. 21. 



A large variety with three-lobed semicells ; lateral 

 lobes subquadrate with rounded angles and straight 

 or slightly retuse sides, polar lobe more widely sub- 

 quadrate with rounded angles and retuse apex. 



Length 57 /n ; breadth 41/*; breadth of apex (polar 

 lobe) 25 fj, ; breadth of isthmus 9*5 /u. 



ENGLAND. Xew Forest, Hants ! Thursley Common. 

 Surrey ! 



WALES. Eadnor ! 



SCOTLAND. Strathpeffer, Ross ; Upper Powlair in 

 Birse, Aberdeen ; Dalbrake, and Bogandreep in 

 Strachan, Kincardine; Glen Clova and Clova Table- 

 land, Forfar ; Folotry Loch in Fowlis Wester, Perth ; 

 near Kingshouse, Argyll (Roy Bissett). Scalloway. 

 Shetlands ! 



