setae, viz. one spatulate and another with a long, drawn-out tip 
(k). The animal has now two pairs of eyes, one pair of smaller 
eyes having appeared dorsally to the original ones. The next stage 
Fig. 1. Eggs and Larvae of Arenicola marina L. X 180. 
(h), with 3 chaetigerous segments, was found on August the 17th; 
the larva had attained a length of 0,248 mm. The two first chaeti¬ 
gerous segments bore crotchets (1), one pair on each. 
Having reached this stage many of the larvae died, and 
the remaining were still on August the 2Ist mostly in the same 
stage. Only one specimen had 3 fully developed chaetigerous seg- 
