REPORTON THE SPONGES 
DREDGED UP IN THE ARCTIC SEA BY THE „WILLEM BARENTS” 
in the years 1878 and 1879. 
BY 
Dr. G. C. J. VOSMAER. 
The Sponges, dredged in the year 1878 by Dr. Sluiter, and in 
1879 by Mr. van Lith de Jeude, and which I hope to describe 
here afterwards, are all preserved in spirits. But all are done in 
toto in liquor, often with many other objects in the same bottle. 
This is the reason that they are not in a fit condition for studying 
many histological details. What I have seen of different tissues, 
I have noticed and illustrated for myself, in order to profit by it 
afterwards. For the moment it seemed to me too full of gaps for 
publication. Thus in the following lines I only give an account of 
the Sponges in a systematic view. Some observations must howe- 
ver be made before I can commence. 
In reading the researches of our recent Spongiolists we every 
time become more convinced that the idea „species” is to be taken 
in a very wide sense. The history of T'henea muricata Gray may serve 
as an example. When | observed specimens of this Sponge for the 
first time, I believed it to be a new species; but after researches on 
some more specimens I soon became convinced 1°. that there was a 
narrow relation between these different specimens, and 2°. that 
VosMAER, Sponges. a 
