228 



were found , thus a very large one (long. — 81 fi; lat. = 68 u) in a 

 glass vessel containing algæ from Nolso; in the same glass another 

 form was noticed which in vertical view had sides somewhat 

 swollen; in a gathering from Trangisvaag a form was met with 

 which closely agreed with var. mesoleia Nordst. (Nordst. et Wittr. 

 Desm. Ital. p. 27, tab. 12, fig. 2), but differed from it in the broader 

 truncated apices of the semicells. Moreover, in some material from 

 Thorshavn var. emarginata Hansg. (Prodrom. Algenfl. fig. 116) was 

 found. The typical form was met with in Plankton from the lake 

 near Ejde (Ost.) and Grothusvatn (Sand 6). 



165. C. margaritiferum Menegh. 



Hojvig (Str.); Klakken near Klaksvig (Bord 6); Sand (San do); and 

 in Plankton from the lake near Ejde (Ost.). 



165. C. Brébissonii Menegh. 



Long. = 92 u; lat. = 67 /*; lat. isthm. = 22 fi; crass. = 48 fi. 



Midvaag (Vaago); Svartafoselv near Hojvig (Str.); Trangisvaag (Syd.). 



167. C. tetraophthalmum (Kiitz.) Menegh. 



»Skaarene« on Bordo (375 m.); Skopen and Sand (Sando). 



168. C. ochthodes Nordst. 



Tliorshavn (Str.); Grothusvatn (Sando); Klaksvig (Bordo). Also 

 found by Wille (1. c. p. 27). 



169. C. annulatum Nagl. ^ elegans Nordst. 

 Long. --^ 46 // ; lat. - 22 fi. 



Hojvig and Skjælling (Str.); Nolso; Klakken near Klaksvig (Bordo). 



170. Arthrodesmus Incus (Bréb.) Hass. 



Aniongst Sphagnum in a bog near Hojvig (Str.). Here found with 

 spores exactly like those in Ralfs's figure (1. c. tab. XX, fig. 4 1). 



Lat. spor. sin. acul. = 19 //; lat. spor. cum acul. = 40 ft. 



In a gathering from Klakken near Klaksvig (Bordo) a similar 

 form was found, it only dilTered in the sides of the semicells being 

 nearly straight and the spines directed somewhat more downwards 

 than in the above-mentioned figure of Ralf. 



Long. = 21,6 /m; lat. — 18 jm; long. acul. = 8 ;w; lat. isthm. = 5 fi. 



Formå. Plate X, fig. 4. 



Long. -— 14/*; crass. = 9 /«. 



This small form resembles var. intermedia Wittr. (Skand. Desm. 

 p. 15, fig. 6), but differs from it, e. g. in the spines being directed 

 outwards in a straight line with the truncated apices of the semi- 

 cells; forms closely related to it are f. islhmosa Heimerl (Desm. alp. 



