Marine Plankton from the East-Greenland Sea. 



313 



water and the interior part of the pack-ice (July 31'^ and Aug. 15*'^ 

 1906) is characterized by the following features: The cell is in 

 ventral wiew rhombic, the epitheca is pointed [acutus) but not tape- 

 ring [acuminatus), the hypotheca ends in two diverging fin-less 

 spines which are distant from the longitudinal furrow. The girdle 

 forms a descending screw to the right. Of the plates of the epi- 

 theca, â is small and almost quadratic whereas y and e are bigger 

 and many-sided. 



17. Peridinium brevipes Paulsen, Nord. Plankton, p. 108, 

 fig. 151 (without description); Broch, Spitzbergen Plankton p. 48, 

 fig. 22. 



In 1908 I published the name and an outline-figure of this spe- 

 cies which I had seen at Iceland. Broch in his paper on Spitz- 

 bergen Plankton gives detailed figures of the species, and these 

 agree well with the annexed fig. 13. Length 36 m (different cells 

 measured). The form of the body 

 and the arrangement of the plates 

 are seen in the drawings. As to 

 the plates, ô is small and qua- 

 dratic, the rhomb-plate being 

 broad and oblique does not touch 

 f but touches b along a vertical 

 line. The two small spines at the 

 lower end of the cell may be 

 wanting. I have seen only spe- 

 cimens with broad intercalary 

 bands, but Broch has them 

 broader yet. After his theory we 

 have then old cells before us, 



but if this is the case it seems 



, .1 . il , 1 // T Fiff. 13. Peridiitiiim brevipes. 375 t. m. 



to me that they cannot be "Ju- " ' 



gendstadium" of P. hreue, what Broch presumes. The adult cells 



are much smaller than P. breve, and also in form they seem to 



differ from P. breve. 



P. brevipes was not common in the samples, but it is very likely 

 that this small organism passes through the net-meshes. It was 

 found in several samples from Danmarks Havn but in few from the 

 coastal water, the pack-ice and the open sea. 



l)i strib. Arctic neritic species, known from Iceland and Spitzbergen. 



18. Peridinium depressum Bailey, in Smithsonian contrib. to 

 knowledge Vll, 1855, p. 12, fig. 33—34; Paulsen, Nord. Plankton 

 p. 53, fig. 67 ; Broch, Spitzbergen Plankton p. 51, fig. 26. 



