INTRODUCTION. 
IN THE Norwegian museums have been stored comprehensive 
and valuable collections of mollusca obtained in the course of 
dredging excursions along the extensive coasts of Norway. Part 
of them belonging to the University Museum at Christiania had 
been placed at my disposal for determination and publication, a 
kindness for which I am indebted to prof. T. Opuner. In dealing 
with the Solenogastres contained in these collections, I met with 
some interesting forms which decided me to extend my investig- 
ations so as to comprise a large material from the Norwegian 
coast. Through the kindness of prof. Brinkmann I received all the 
forms contained in the museum at Bergen, and among these re- 
mained fortunately also the old types established by Koren & 
DaniELsseN, which had been considered as lost. This happy cir- 
cumstance has enabled me to make a revision of these types, the 
original descriptions of which are so unsatisfactory that the re- 
spective forms have hitherto been unidentifiable. These species 
have now been arranged in their definite position in the prevalent 
system of classification, i. e. they have been allotted to modern 
genera, and their organization has been described and illustrated. 
Besides the collections in the above-mentioned Norwegian mu- 
seums, all other material of this group of animals collected on 
the coasts of Norway and accessible to me is dealt with in the 
following pages. Thus I am indebted for collections sent by dr. 
Tx. Mortensen, Copenhagen, prof. L. A. JåGerskiöLp, Gothen- 
burg, and dr. O. Norpcaarp, Trondhjem. The present publication 
thus contains as exhaustive as possible a survey of the Nor- 
wegian Solenogastres, which appear to be represented by a rather 
large number of interesting types. One new family and two new 
