3 
ments with 2 pairs of setae and one pair of crotchets each; some 
few days later no living larvae were to be found. 
During several years I have known these larvae of Arenicola, 
and in the free nature I have caught such larvae with 5 chaeti- 
gerous segments (in September), but between this stage and the 
„post-larval“ Benham-stage (see Ashworth 1. c. page 268) which 
I have found occurring in numbers in early spring (April—June) 
by Nyborg, I miss the transitional stages. But my experiences ap- 
pear to prove that Arenicola by us breeds during the autumn 
(Ashworth [1. c. page 211—212] says in the spring), and that the 
duration of the pelagic life of the larva is very considerable, ex- 
tending, perhaps, over the whole winter time. Further investigations 
are, however, necessary to solve this question. _ 
24—3—1923. 
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