Evolution 
As to the origin of the Enteropneusta, opinions are somewhat 
divided. Their blood system and their development would seem 
to suggest a descent from the ringed worms. On the other hand, 
their possession of a snout, and their very slight indication of 
division into segments, would seem to separate them from the 
group mentioned and to connect them rather with the Nemertines. 
The latter view is perhaps the more probable. 
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