233 



Formå 2 gona: Long. = 28—30 jm; lat. sine aciil. = 22 jw; crass. 

 — 14 jm; lat. cell. cum acul. — 64 fi; long. acul. — 22 /j. 



In Plankton trom Sorvaagsvatn (Vaago). 



It secms to nie Ihat Arthrocicsiuns loiujUornis Roy (Roy&Biss.: 

 On Scottish Desmidieæ p. 28 (sep. !), tab. 4, lig. 1) must undoubtcdly 

 be referred to my two-sided >^Arthrodesmiis< form, it only differs 

 from it in the spines being less diverging; and also Borge in a 

 short paper: »Siisswasseralgen aus der Inscl Mull« (in Bot. Notiser 

 1897 p. 213) not only mentions forms like Roy's figure, bnt also 

 reports having found cells with more diverging spines (cfr. fig. 5 a) 

 which quite correspond to my figure. In the same paper Borge 

 gives a figure of a form oi Staurastrum megacanthiim with long spines; 

 but it is easily distinguished from the species in question by ils 

 cells which are far broader. 



199. S. lunatum Ralfs. 



A form like Borge's figure (Algologiska Notiser 4, p. 213, fig. 8) oc- 

 ciirs in Plankton from Sorvaagsvatn (Vaago); and lake near Ejde (Ost.). 

 A form witli consideraJjly sliorter spines was found in a gatliering of 

 algæ from Skopen (San do). 



200. S. cpistatum (Niigl.) Arch. 

 Long. = 30 (W x= lat. 

 Gliversrejn near Thorsliavn (Str.). 



201. S. Avicula Bréb. 

 Grothusvatn (S a n d o). 



202. S. denticulatum (Niigl.) Arch. 



In Plankton from Sorvaagsvatn (Vaago). 



203. S. rostellum Roy c^ Biss. Plate VII, fig. 15. 

 On Scott. Desm. p. 24, tab. IV, fig. 3. 



The specimens found by me in the Færoes dilfer at first sight 

 with their many bifurcate spines considerably from Roy & Bisset's 

 figure. But on regarding their figure more closely one not only 

 discovers here and there in it a bifurcate spine, but the two down- 

 ward directed spines at the angles of their figure in front view also 

 have smaller ones on them ; therefore I do not hesitate to refer 

 my form to this species even if it may be that it is also vcry like 

 the below-mentioned form of St. sjjongiosum. 



Long. cum acul. — 32 fi; lat. — 21^; lat. istm. — \\ ^. 



In gatherings from Gliversrejn and Skjælling (Str.). 



