12 Algae. 



chaeolithothamnion gestellt und {LithophyllumY) belgicnm Fosl. neu 

 beschrieben. N. Wille. 



Ostenfeld, C. H., On the Immigration of Biddulphia sinensis 

 Grev. and its occurrence in the North Sea during 1903 — 

 1907, and on its Use for the Study of the Direction and 

 Rate of Flow of the Currents. (Meddelelser fra Kommissionen 

 for Havundersögelser. Serie Plankton. I. 6. 44 pp. with 4 Charts 

 and 5 text-figs. Köbenhavn, 1908.) 



During the quarterly cruises carried out by the states which 

 take part in the International Cooperation for the Study of the Sea, 

 plankton collections have alwa}^s (from 1902 up to now), been made 

 and the samples have been examined by the specialists of each 

 State, the results being published jointly in a periodical „Bulletin" 

 issued from the Central Bureau. 



In the samples from the November 1903 cruise a large diatom 

 Biddulphia sinensis suddenly was present within an area of the 

 North Sea which extended westwards to ca. 40 E. Long., south- 

 wards to the mouth of the river Elbe and eastwards to the Skager 

 Rak and Kattegat to ca. 56°30' N. Lat., and in many of the sam- 

 ples it was the dominant species. It had not before been found in 

 the North Sea area and was altogether a new inhabitant of the 

 Atlantic Ocean 1 ), while widely distributed along the tropical and 

 subtropical shores of the Indian Ocean and adjacent parts of the 

 Pacific Ocean. 



This immigration seemed to the author to be of great interest, 

 and therefore he tried to study it as closely as possible during the 

 following years. The results of his studies are published in the pre- 

 sent paper. 



The characters which separate B. sinensis from related species 

 are given, summed up in a key. Two species are nearly allied to 

 it, B. mobiliensis (Bail.) Grün, and B. regia (M. Schultze) Ostf., nov.- 

 comb.; both these and B. sinensis are figured. 



By the sudden appearance within a restricted area of the 

 North Sea Area and by other reasons it seems improbable that 

 Bidd. sin. was carried into the North Sea by the currents; it is fur- 

 ther improbable that it was stationary in the North Sea earlier 

 than 1903. The author then concludes that it has been drawn in 

 from afar by the aid of man, i.e. carried along from distant oceans 

 (probably the Indian Ocean) by ship, e. g. attached to the outside 

 or living in the water of the hold , or in the water of a used bücket 

 of one of the many steamers which trade to Hamburg. In accor- 

 dance with this supposition is that its first recorded occurrence in 

 the North Sea is in the S. E. corner, consequently off Hamburg. 



Its distribution and wanderings in the North Sea Area during 

 the next years (1904—07) are given in detail in the text and illu- 

 strated in the Charts, based upon the quarterly cruises. It has its 

 maximum development in November, decreases then tili February, 

 more so tili May, and reaches in the summer its minimum from 

 while it increases rapidly in number after August, again attaining 

 a new max. in November. Its area grows somewhat larger during 



I) In the paper here reviewed the author quotes a record of it from the sea of 

 Guyana upon the authority of the late Prof. Cleve, but he has since examined 

 Cleve's material and has found that the determination was wrong (cfr. Internat. 

 Revue Hydrobiol. and Hydrograph. 1909). 



