Norwegian Solenogastres. 79 
coelomic endothelium of forms such as Annelids. Our view differs 
from the latter in supposing that the coelomic endothelium (or 
the walls of the gonads) and the blood vessels of Solenogastres 
and Mollusca have developed independently from each other 
taking their origin from a still indifferentiated mesenchyma, thus 
from conditions more primitive than those prevailing in the Anre- 
lids and characteristic of parenchymatic unsegmented worms. 
