576 



A boreal-arctic, neritic species, found only once (April 1898) in the 

 plankton. 



Note. C. radians Schiitt belongs to tliis section. — 



Besides the sections mentioned above there are several other sections, the 

 species of which are not found in the plankton around the Færoes. Between 

 Cglindricae and Constrictae I think Protuberantes may be placed, to which C. di- 

 dgmum (Ehbg. Cleve, C. longicrure (Cleve) Ostf. and C. protuberans Laud. belong; 

 the section Subtiles with C. subtile Cleve and C. longisetum Cleve approach Steno- 

 cinctae. As a section fairly rich in species may be named Communes, including 

 C.crinitum Schiitt, C. pseudocrinilum Ostf., C. ballicum Cl. (= C. Granii Cl.) 1 , C. seir- 

 acanthum Gran, C. difficile Cl., C. bottnicum CL, C. caspicum Ostf., C. slrictum Ostf. and 

 perhaps C. perpusillum CL, if the latter is not a dwarf-form of C. Schåttii. Further 

 C. curvisclum CL, C. secuudum Cl. and perhaps C. ciliatum Laud. form the section 

 Curvisetae. Near to the section Compressae I think we may place a section Diversae 

 with C. diversion CL, C. furca Cl. and C. /aeue Leud-Fortm. C. anastomosans Grun. 

 and perhaps C. calvum Cleve form the section Anastomosantes, and lastly we have 

 a section Simplices of the species C. septentrionale Oestr., C. gracile Schiitt, C. simplex 

 Ostf. and C. clavigerum Ostf. — Gran in his last treatise on plankton (Das Plankton 

 d. Norw. Nordmeeres, 1902) mentions a » Chaetoceras Ingolfianum Ostf. in litt.«; it is 

 a small species the endocysts of which differ from the hitherto known type of 

 endocysts in the genus, and resemble the organisms which have been described as 

 Xanthiopgxis. But the examination of this species not being finished, I cannot say 

 anythins definite with reference to this curious faet. 



B. Pennatae. 



FRAGILARIEAE. 



XVII. FRAGILARIA Lyngbye, 1819. 



49. F. oceanica Cleve, Arctic Sea, 1873, p. 22, PI. 4, fig. 25a,b; 



Gran, Bibliotheca Botanica, 42, 1897, p. 8, PI. I, figs. 6—9. 



A few specimens of a chain-forming Fragilaria which I think is 

 identical with F. oceanica was onee found in the plankton (July 1897); 

 it is an arctic, neritic species. 



XVIII. THALASSIOTHRIX Cl. & Grun., 1880. 



50. T. Fraunfeldii Grun., K. Sv. Vet. Akad. Handl. 17, No. 2, 



1880, p. 109. 



A few specimens of this characteristic species (nearest f. javanica 

 Grun.) was found in the plankton from March (three times). 

 Temperate, oceanic species. 



51. T. longissima Cl. ev Grun., K. Sv. Vet. Akad. Handl., 17, 

 No. 2, 1880, p. 108. 



1 Gran (Das Plankton des Nordmeeres, p. 179) has named this species C. lene 

 Schiitt, but it is a newer name than C.laeve Leud-Fortm. (which is very different 



Ironi it , and must tlieiclbre be omiltcd. 



