PREFACE. 



T^ 



he present study was planned several years ago, but other work, 

 especially on Arctic geology and paleontology, has delayed its final conclusion 

 until now. 



M\' investigations exclusively deal with material from the Paleontological 

 Museum ot' the University of Kristiania, brought together during a long space 

 of time, — more than half a century. As regards those who should be 

 mentioned as having contributed very considerably as collectors of the brach- 

 iopods that are here described, as well as of other groups of fossils, we have 

 the directors of the Museum at different times. Professors Kjerulf, Brøgger 

 and Kiær. The latter especially has gathered exeedingly large collections of 

 fine material. A considerable series of collections have also been made by 

 Th. MC.vster, Norwegian Superintendant of Mines, and, during the last 9 

 years, b)' the present author. 



I desire to express here my heartiest thank to the present director fo 

 the Paleontological Museum, Professor Dr. Joh.\.\ Kiær for his kindness in 

 placing at my disposal the material necessary for my studies. 



During a stay at the Geological-Paleontological Museum of Yale University, 

 New Haven, Coim., U. S. A. in 1913 1 had an opportunity of looking through 

 a part of my material that 1 had taken with me to America in the company 

 of the eminent authority on Brachiopods, Professor Schuchert of Yale, and 

 of comparing it with American Strophomenids of Schlxhert'.«; collection. For 

 his kind assistance, which has been of very great importance to the present 

 contribution, 1 herewith express to Prof. Schlxhert my sincere thanks. 



I have derived great assistance in my studies on the Norwegian Stropho- 

 menids from a very large collection of Russian forms, the Strophomenid material 

 of the Paleont. Museum of the Imperial Academy of Sciences of Petrograd, 

 sent to me for study several years ago bj- the late Academician Th. Tscher- 

 xvscHEw. Ha\Tng thus been able to study in well preserved, typical speci- 

 mens the forms originally described from Russia, it has been possible to 

 make reliable identifications in cases where the ft-agmentary state of the 

 Norwegian material otherwise would not have allowed any certain decision. 



Kristiania, December 191 5. 



O. H. 



