The plankton samples collected during the Da n m ar k-Exped i - 

 ti on by Mr. A. LuNDAGER mav be grouped in the following 

 categories : 



1. Samples collected in the open ocean east of the Greenland 

 ice on the way out in 1906 and homeward in 1908. Like Dr. Osten- 

 feld, who has worked out the Diatoms and Flagellates, I think 

 these samples are of no special interest. All of them have been 

 taken in July — August, and on the way home they were collected 

 with so small intervals that it has been quite sufficient to examine 

 only a selected number of them. 



2. Samples collected in the drifting ice (pack-ice) off East Green- 

 land in August 1906 as the "Danmark" went in to the Greenland 

 coast, and in July 1908 when it was homeward bound. On the way 

 out a great many samples were collected, until 12 in a day and a 

 night, and as the speed w^as moderate and the course very curved 

 they are very close together and many of them quite like each other. 

 Therefore, only a certain number of them has been thoroughly 

 investigated. 



3. Samples collected in August 1906 and July 1908 near the 

 coast of East-Greenland, from off Koldewey Island (ca. 76° 30' N. Lat.) 

 to ca. 78° N. Lat., thus in the coastal water. 



4. Samples collected in Danmarks Havn (Denmark harbour), 

 at 76° 46' N. Lat., 18° 43' W. Long., where the expedition stayed 

 about two years, from August 1906 till July 1908. Unfortunately 

 these samples were not taken with regular intervals but rather 

 occasionally : there is about a dozen of samples from the summer 

 1907, and in 1908 samples were collected on July 21** when "Dan- 

 mark" left the harbour. 



In the following pages a list is given of all the Peridiniales 

 found in these samples, and some of the species are accompanied 

 by figures and remarks. A general description of the plankton will 

 be giwen in a concluding paper by Dr. Ostenfeld and the present 

 author. 



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