COSMARIUM. 157 



This is a characteristic species which occurs amongst mosses 

 on wet rocks in mountainous or alpine areas. In the British 

 Islands it appears to be very rare. 



It is distinguished from C. pseiidopymmidatum Lund, and 

 C. variolatum Lund, by its much shallower constriction, its 

 rounded apices, its more densely punctate cell-wall, and by 

 the tumour at each side of the vertical view. 



Forma parvula "Wille. (PI. LX, fig. 9.) 



C. microsphinctum Nordst. forma parvula Wille, Ferskv. Alg. Nov. Semlj. 

 1879, p. 38. t. 12, f . 22 ; Eoy & Biss. Scott. Desm. 1894, p. 168. 



Cells a little smaller and proportionately a little 

 longer ; seniicells more attenuated to a narrower apex. 



Length 33 /i ; breadth 20 /a ; breadth of isthmus 7 /u ; 

 thickness 15^. 



SCOTLAND. Kemback near St. Andrews, Fife (Roy 

 Blssetf). 



Geogr. Distribution. Nova Zembla. 



Var. majus Roy & Biss. (PL LX, fig. 10.) 



C. microsphinctum Nordst. var. majus Eoy & Biss. Scott. Desm. 1894, 

 p. 168, t. 4, f. 7. 



About twice the size of the ordinary form. 



/ 



Length 80 n ; breadth 52 ^ ; breadth of isthmus 35 /n. 

 SCOTLAND. Presswhin in Cromar, Aberdeen (Roy 

 Bissett). 



17. Cosmarium morsum West. 

 (PL LX, fig. 11.) 



Cosmarium morsum West, Alg. Eng. Lake Distr. 1892, p. 729, t. 9, f. 10; 

 Nordst. Index Desm. 1896, p. 176. 



Cells rather small, almost twice as long as broad, 

 slightly constricted, sinus widely open and semicircular; 

 semicells semi-elliptic, basal angles rectangular. Side 

 view of semicell subcircular, with the sides somewhat 

 compressed. Vertical view very broadly elliptic, ratio 

 of axes about 1 : 1'2. Cell-wall smooth. 



Zygospore unknown. 



