Preface. 



It is now about four years since my friend. Dr. Fridtjof Nansen asked me if I would join bim in a work on tiie 

 tine collection of ^^'bale embryos contained in tbe Bergen Museum, and whicli,. to a great extent. Dr. Nansen himself, when 

 curator of that museum, assisted by the curator, James Grieg, had brought together. As the committee of management were 

 favorably disposed towards Dr. Nansen's proposal, I was quite willing to enter into so interesting a labour, the more so from 

 my having formerly been greatly interested in Cetacea. 



In the autumn of 1890, some small embryos of Lagenorhyn chus acutus were sent to us in Christiania, where 

 Dr. Nansen was also residing, having been made fellow of the University after his Greenland expedition, and keeper of the 

 zootomical collection in the Royal Norwegian University of Christiania. 



In the summer of 1891, I spent some time in Bergen in order to become better acquainted with the large collection 

 of embryos and foetuses belonging to the museum there; and I would here offer my sincerest thanks to Dr. Danielssen') and 

 the officers of the museum. Dr. Brunchorst, Dr. Appelliif and James A. Grieg, for the friendliness and good will 

 there shown me. 



During the winter of 1891 — 92, Dr. Nansen and I worked together in the laboratory of the Anatomical Institution, 

 studying more particularly the small embryos of Lagenorhynchus acutus, Gray. Later on, we had only occasional meetings 

 for consultation about the work, as Dr. Nansen, being occupied with preparations for his North Pole Expedition, left it entirely 

 to me. Dr. Nansen, as is well-known started on his Polar Expedition in June, 1893. 



Owing to the numerous duties of my ofhce, and to other c;dls upon my time, the completion of this work has 

 been delayed for about two years, as I did not resume it until August, 1893. In the mean time, the material had been 

 increased by the addition of a lew interesting small embryos of Phocæna communis which I received from Greenland, 

 through the University's Zoological Museum. In these I was able to show the existence of rudimentary hind-limbs. I spoke 

 of this discovery and demonstrated it at the Anatomical Congress in Strasburg, on May 14th, 1894. 



In addition to the species Lagenorhynchus acutus, L. albirostris, Phocæna communis and Orca 

 gladiator, I have examined several embryos of Globicephalus melas and Delphinapterus leu cas, and to some extent 

 Delphinus delpliis. With the last three species, however, I have not dealt in this treatise, as its publication would thereby 

 have been still further delayed. 



Our special thanks are due to the trustees of the Bergen Museum for the liberality with which the work has been 

 got uj), and to Miss Jessie Muir in Christiania for the care and labour bestowed upon its translation. 



Christiania, July, 1894. G. GULDBERG. 



') Sini'f writinjr these lines. 1 have receiveil the sad intelligence of Dr. Danielssen's death. 



