142 BRITISH DESMIDIACE2E. 



rounded granules, winch vary considerably in disposi- 

 tion, and sometimes with minute inter granular scrobicu- 

 lations. Side view of semicell ovate, upper parts of 

 sides retuse, apex subtruncate, basal tumours with 4 

 marginal granules, apex 4-granulate, and with a band 

 of emarginate warts in 4 parallel series extending from 

 just above the isthmus to the apex. Vertical view 

 elliptic, ratio of axes about 1 : 1*5, poles subtruncate 

 and furnished with 4 granules, with a broad tumour 

 (4-granulate) at the middle on each side, and with 4 

 parallel series of emarginate warts extending from 

 pole to pole. Cell-wall often minutely punctate. 

 Chloroplasts axile, with two pyrenoids. 



Zygospore quadrate-rectangular and smooth, angles 

 a little produced, rounded or subtruncate (rarely 

 retuse), sides straight or slightly convex ; the two angles 

 of one end of the zygospore sometimes twisted into a 

 plane at right angles to that containing the other two. 



Length 40-57 ' 5 /* ; breadth 32-39 /*; breadth of 

 isthmus 10-16 //,; thickness 20-26*4 /x; length of 

 zygosp. 40-48 ^ ; breadth of zygosp. 84-36 JJL. 



WALES.- -Capel Curig !, Glyder Fawr (Roy), and 

 Llyn-y-cwm-ffynon !, Carnarvonshire. 



SCOTLAND.- -fehiconich, Sutherland! Skye, Glen 

 Nevis, and Invermoidart, Inverness ! Near Longside, 

 Aberdeen; Glencoe, Argyll; Goat Fell and Glen Raiiga, 

 Arran (Roy fy Bissett) . Common in the Outer Hebrides 

 (zygospores from near Tarbert, Harris) ! 



IRELAND.- -Kylemore and Bally nahinch, Galway ! 

 Adrigole, Castletown, and Carrantuohill, Kerry ! 



Geoc/r. Distribution. Saxony. Norway. Sweden. 

 Greenland. Ceylon. Java (form). New Zealand. 

 United States. Brazil (var.). Patagonia. 



C. quadrifarium often occurs associated with C. monomazum 

 var. polymazum, and,, like that Desmid, it appears to have a 

 western and north-western British distribution. It is a very 

 characteristic species, with an equally characteristic zygo- 

 spore, although it shows a considerable variation in the details 

 of arrangement of the central granules, and in the number 



