Algae. 141 



qu'il existe im pyreno'ide (non inclus dans lcs chromatophores, 

 comme c'est la cas habituel) dans les Cryptomonas erosa et cyanea. 

 II en a observe un chez le Rhodomotias battica Karsten qui pour 

 Lemmermann est identique au R. marina Lemm. et par suite au 

 C. marina Dangeard. D'ailleurs les deux genres sont difficiles ä 

 distinguer dans la pratique, les Rhodomonas possedant seulement 

 un chromatophore tandis que les Cryptomonas en poss^dent deux. 

 Le R. marina est photophobe; il se multiplie par division longitu- 

 dinale et peut se presenter en colonies palmelloides. 



La presence ou l'absence de pyreno'ide sert chez les Algues a s€- 

 parer des genres. La note de Dangeard pose la question de savoir 

 si les corpuscules amyliferes semblables aux pyrenoides chez les 

 Cryptomonadinees permettra d'etablir des divisions generiques sui- 

 vant la presence ou l'absence de ces corps. P. Hariot. 



Paulsen, O., The Plankton on a submarine Bank. (Biol. 

 Arb. tilegnede Eug. Warming. Köbenhavn, p. 231 — 239. 1911.) 



Southwest of the Färoes in the North-Atlantic Ocean a 

 large submarine bank is situated; the smallest depth is ab. 100 m., 

 and the bank slopes rather steeply on all sides, the 600 m. curve 

 is at a distance of 10 — 50 miles from the 200 m. curve. 



During the cruises of the Danish marine investigation steamer 

 •Thor" the author has examined the plankton of this submarine- 

 bank, and has found that it was different from the plankton of the 

 surrounding water. The investigations have been made in May and 

 September 1904 and in March and May 1910. The present paper 

 deals mostly with the conditions in May 1910. Taken as a whole 

 the bank plankton has a more "neritic" character than that of the 

 surrounding water, and mostly its quantity is much greater; the 

 main part of the phytoplankton are diatoms, in May 1910 especially 

 4 species of Coscinodiscns. From the examination of the samples 

 taken it becomes evident that the bank plankton is rather indepen- 

 dent lying as a cloud in the midst of a different and more "oceanic" 

 plankton. The hydrographical investigation of the bank and its 

 surroundings has shown that the bank water is different from the 

 surrounding water, being a little colder and fresher at the same 

 depth. The hydrographer Martin Knudsen is of the opinion that 

 the bank water is formed through currents and mixing processes 

 along the edge of the bank, so that the deeper water layers are 

 brought up over the bank. This agrees with the greater quantity 

 of the bank plankton, as A. Nathansohn has shown that vertical 

 circulation can call forth sudden plankton maxima. The conditions 

 in Ma} r 1910 seem to show that the new water — in which no 

 phytoplankton has lived and which, therefore, is favourable to the 

 development of phytoplankton — came first to the N.-E.-Side of 

 the bank where the greater quantity of plankton was found. As to 

 the term "neritic" the author suggests "that the proper nutritive 

 qualities in the water is the first condition for the development of 

 neritic plankton." C. H. Ostenfeld. 



Perrot, E. et C. L. Gatin. Les Algues marines utiles et en 

 particulier les Algues alimentaires d'Extreme-Orient. 

 (Ann. Inst, oceanographique. III. 1. 101 pp. 12 fiff. dans le texte. 

 10 pl. hors texte. 1911.) 



Le travail de Perrot et Gatin est divise en trois parties. La 



