4 INTRODUCTION 



All the samples of plankton have been examined by me, both 

 for animals and plants. The observations were registered month by 

 month, and the results brought together so as to show for each 

 month the area of distribution for all Atlantic plankton organisms. 



In order to render these observations more complete I also 

 made use of a number of data published by Ostenfeld, by George 

 Murray & F. G. Whitting and by Aurivillius*. 



For every species I have calculated the mean temperature and 

 salinity and indicated the maxima and minima. In calculating these 

 averages for species that occur gregariously I have only used, as 

 a rule, such samples as contained the species in question abundantly. 



In spite of the great number of observations obtained, the survey 

 of the plankton of the Atlantic is by no means to be considered as 

 a complete one, as samples were not collected from all parts of the 

 ocean every month. In order to show to what extent the survey 

 has been carried out it will be necessary to state what parts of the 

 ocean have been examined each month. I therefore prepared the 

 following 



List of routes and stations, where samples 

 have been collected: 



1897 December: Dutch Steamer »Pi'ins Fredei'ik Heiu:Irik»: 19"' 

 to 3r'\ from 45° N. 13° W. to 12° N. 50° W. — Number of 

 samples 13. 



1898 Janiiary: Dutch Steamer »Prins Wlllein T"».- 17"' to 30'', from 

 48° N. 6° W. to 11° N. 52° W. Dutch Steamer »P/'//?.s Fre- 

 dcrik Hen(Ink»: 1"' to 30^ from 7° N. 53° W. to 37° N. 

 73° W. French Steamer >>Les Alpesy> : 15"' to 28"', from 34° N. 

 14° W. to 17° S. 38° W. — Number of samples 41. 

 February: Swedish Corvette y>Fjv^i/a»: 22*^ to 28"', from 6° S. 

 12° E. to 5° S. 0° W. French Steamers »La Gascogne»: 27"' 

 and 28"', from 50° N. 7° W. to 49° N. 17° W. and »La Cham- 



* Ostenfeld: lagttagelser over overfladvandets temperatur, saltlioldighed og 

 plankton paa islandske og gronlandske skibsrouter i 1898, foretagne under ledelse 

 af C. F. Wandel, Copenh. 1899. 



G. Murray & Whitting: New Peridiniacea from tlie Atlantic. Trans. Linn. 

 Sec. of London 2nd Ser. Botany. Vol. V. Part. 9, 1899. 



Aurivillius: Kongl. Svenska Vetenskaps-Akademiens Handlingar. Vol. 

 XXXII, No 6, 1899. 



