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the summer of 1920 Mr. G. L. Gruelund at my request undertook to 

 collect a series of plankton samples (by means of the wash-deck pump) 

 on a trip to Buenos Aires. The result was remarkably poor, only two of 

 the samples containing any Echinoderm larvae at all ; still some information 

 was gained hereby also. Further, Mr. H. Faye, St. Cruz, West Indies, 

 undertook to collect some plankton samples for me in the harbour of 

 Christianssted, which contained several interesting Echinoderm larvae. 

 To all these gentlemen I beg to tender my best thanks for this assistance. 

 Plankton samples were generally taken at the different places in the Pacific 

 where longer stay was made; not few important and interesting forms of 

 larvae have been secured in that way, especially of the Ophiuroid-larvae 

 which are generally found quite well preserved in such plankton samples; 

 descriptions of such forms are included in the following report. On the 

 author's expedition to Siam in 1899 — 1900 there were also collected several 

 Echinoderm larvae, which are likewise included in the present report. — 

 It may, however, be emphasized that by no means all the larvae thus 

 collected have been described here. Only such as were found to present 

 special and noteworthy features or that could be identified with forms 

 hitherto described and thus affording zoogeographical information have 

 been included. 



It is a very agreable duty to me to express my indebtedness and sincere 

 thanks to all those authorities and colleagues who have rendered me 

 assistance on my voyage or otherwise in connection with this work. First 

 of all my thanks are due to the Carlsberg Fund which by its liberal 

 grant made it possible for me to realize my plan of the Expedition to the 

 Pacific, and from which grants were also received for publishing this 

 report. A special grant was also given me from the Danish Govern- 

 ment for enabling me to complete the reports on the material from my 

 voyage. — Adopting a chronological arrangement I then beg to address 

 my sincere thanks to the director of the Biological Station at Misaki, 

 Japan, Professor I. I Jim a, Tokio, and Dr. Fujita, then Assistant at the 

 said Biological Station; to Professor W. A. Haswell and Dr. S. Johnston, 

 at the University of Sydney; Professor H. B. Kirk, Wellington; Professor 

 W. A. Bryan, Honolulu, and Mr. D. Thaanum, Hilo, Hawaii; Dr. 

 Ch. MacLean Eraser, Director of the Biological Station, Nanaimo, 

 Vancouver B. C; Professor Wm. Hitter, Director of the Biological Sta- 

 tion of the Scripps Institution, La JoUa, California; Professor James 

 Zetek, Panama, and Professor A. G. Mayor, Director of the Depart- 

 ment of Marine Biology of the Carnegie Institution, Washington D. C. 

 A special thank I owe to the New Zealand Government for inviting 



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