cosMARTinr. 163 



22. Cosmarium asphserosporum Nordst. 

 (PI. LX, figs. 24, 25.) 



Cosmarium Schliephackeanum Rabenh. forma spetsbergensis Nordst. Desm. 



Arctoae, 1875, p. 24, t. 7, f. 15 ; Cooke, Brit. Desm. 1886, p. 92, t. 37, 



f . 10 ; Eoy & Biss. Scott. Desm. 1894, p. 174. 

 C. asphserospomm Nordst. in Wittr. & Nordst. Alg. Exsic. 1879, no. 268 ; 



fasc. 21, 1889, p. 49; West & G. S. West, Alga.-fl. Yorks. 1900, p. 74. 

 Ursinella asphserospora Kuntze, Revis. gen. plant. 1891, p. 924. 



Cells small, about as long or not quite as long as 

 broad, moderately constricted, sinus widely open, sub- 

 rectangular with an obtuse apex ; semicells broadly 

 cuneate, with a widely-truncate apex and rounded 

 angles. Side view of semicell obovate-subcircular 

 from a broad base. Vertical view subrhomboid-elliptic, 

 with a scarcely- evident, depressed wart at the middle 

 on each side, ratio of axes about 1 : 1*27. Cell-wall 

 smooth and colourless. 



Zygospore smooth, subrectangular-oblong, some- 

 times elliptic or somewhat irregular, angles rounded, 

 longer sides convex in the middle, shorter sides retuse; 

 side view elliptic; end view circular; cell-wall lead- 

 coloured. 



Length 10-13 //, ; breadth 12-13 /* ; breadth of isth- 

 mus 7-8/x,; thickness 9-10 p; length of zygospore 

 21-22 p. ; breadth of zygospore 14-18 /x. 



ENGLAXD. Penvsrhent, W. Yorks ! 



/ O 



SCOTLAND. Inverness, Aberdeen, Kincardine, Forfar, 

 Perth, Stirling, Argyll ; zygospores from Dinnet, 

 Aberdeen, and Kerloch, Kincardine (Rot/ fy Bissett). 



Geogr. Distribution.- -Norway. Sweden. Spitsbergen. 

 Xova Zembla. Xew Zealand (var.) United States. 



This species is distinguished from C. bioculatum Breb. and 

 C. tenue Arch, by its much shallower constriction and widely- 

 open sinus, by the subtruncate apices, by the form of the 

 vertical view,, and by the characteristic shape of the zygo- 

 spore. It differs from C. inconspicuum West & Gr. S. West in 

 its relatively greater breadth, its broader, subtruncate apices, 

 its rhomboid vertical view, and its rectangular zygospore. 



