508 



19. D. tenuis (Cleve) Gran, Plankton des Norw. Nordmeercs, 



1902, p. 172; I), mediterranelis v. tennis Cleve, Fish. Board for Scot- 



land 1897, p. 300, fig. 14. 



This s]>ecies also is found once only and in a l'ew specimens (Sep- 

 tember). In the North Atlantic Ocean the two species often occur together. 



XI. GUINARDIA Perag., 1892. 



20. G. flaccida (Castr.) Perag., Monogr. Rhiz., p. 107, PI. I, 



figs. 3—5. 



A temperate, neritic species found along the west coast of Enrope 

 and Africa (also in other Oceans). Around the Færoes only found in the 

 some samples from Klaksvig (August), in which Lauderia borealis occurs. 



XII. RHIZOSOLENIA (Ehbg.) Btw., 1858. 



21. R. delicatula Cleve, Plankt. of the North Sea, Kgl. Vetensk. 

 Akad. Handl., Bd. 32, No. 8, 1900, p. 28, fig. 11; Leptocylindrus dani- 

 cns Schiitt, Jahrb. f. wissensch. Botanik, XXXV., 1900, PI. XII, figs. 

 13—24, 33; non Cleve. 



A boreal, neritic species found in the English Channel and the 

 North Sea (and but rarely around the Azores) is moreover characteristic 



of the plankton of leeland (according to 

 (i ran). Found four times at the Færoes in 

 July — August, but sparingly. 



22. R. faeroénsis n. sp. Cells short- 

 cylindrieal with blunt angles, length 50 — 

 80 |M, breadth 40 — 70 ja ; spine very Ihin 

 and short, forming the centre of a bluntly 

 triangular depression on the valve; nunie- 

 rous connecting rings; chromatophores 

 rather numerous; occurs singly or in cbains. 

 Related to R. delicatula and R. Stolterfothii. 

 This very peeuliar Rliizosolenia, which 

 at the (irst glance resembles Ceratanlina, 

 seems to l)e an outpost of the genus, 

 forming a transition to the La uderia-group 

 and perhaps also to Ditylum; il comes 

 nearest to R. delicatula, of which I have 

 given a ligure from the same sample for comparison. 



It occurs in plankton from July 1900 and August 1902 and is 

 ralhcr common in some of the samples; il was also found in July 1897, 

 judging Ironi ;i drawing in my nianuscripl notes of the planklon of thai 



Fig. 123. Fig. 124. 



Fig. 123. Rhizosolenia delicatula Cl., 

 chain showing the arrangement ofthe 



chromatophores (""/i). 

 Fig. 124. Rhizosolenia faeroénsis Ostf., 

 n. sp « chain of 4 cells showing the 

 connections; b cell with connecting 

 rings; c cell with chromatophores; 

 <( cell in side vicw ('"/i). 



