COSMAEIUM. 59 



Siberia. Greenland. Xew Zealand (form). United 

 States. AY. Indies. Patagonia (form). 



C. quadratum is a characteristic species with a wide distri- 

 bution, but is of much more general occurrence in the up- 

 lands than in the lowlands,, especially in the Sphagnum bogs. 

 The basal angles of the semicells are rounded,, and are very 

 slightly turgid and protruding. This character, the slightly 

 open sinus,, the retuse sides of the semicells, and the axile 

 chloroplastSj distinguish C. quadratum from C. Cucumis, a 

 species with which it should be compared. 



We fio-ure one individual with a slight irreo-ularitv in the 



C o i< 



chloroplasts (PI. LXXXYII, fig. 19). The chloroplast of one 

 semicell is normal in the possession of two pyrenoids, but 

 that of the other semicell possesses three pyrenoids. 



Forma Willei nob. (PL LXXXYII, figs. 21, 22.) 



Cosmariv.m quadratum Ealfs forma " semicellulc? lateribus 



latissime rotundatis 1. rectis nee retusis' : AVille, Ferskv. Al<_r. Nov. 



Seinlj. 1879, p. 37, t. 12, f. 20, 21 [Indus, f. major "\Ville~ : Boldt. Siber. 



Chlorophy. 1885, p. 100 ; Desm. "Gronland, 1888, p. 10"; Borge, Sussw. 



Chlor. Archang. 1894, p. 23. 

 Dyspliinctium quadratum (Ealfs) Hansg. var. Willei Sclimidle, Beitr. 



Algenfl. Sclnvarzwald. u. Eheineb. 1893, p. 91, t. 4, f. 1, 2. 



Sides of semicells straight or slightly convex. 



o / 



Length 50-76 p. ; breadth 30-46 p. ; breadth of isth- 

 mus 16*8-27 p. ; thickness 27-36 JJL. 



ENGLAND.- -Helyellyn, Westmoreland ! Mickle Fell, 

 X. Yorks ! 



IRELAND. Jar Coniianght, Gahvav ! Carrantnohill, 

 Kerry ! 



Geoc/i: Distribution. Xova Zembla. Grreenland. 

 X. Russia. Siberia. 



Var. angustatum var. nov. (PI. LXXXVII, fig. 20.) 



Cells proportionately narrower, about 2 J times longer 



than broad, shins rather more open. 



Length 7 Op.', breadth 30 p.; breadth of isthmus 

 20 JLC ; thickness 25*5 p.. 



ENGLAND.- -AVoodbury Common, near Exeter, Devon- 

 shire ! (E. Mornan}. 

 \ i> / 



