EXPLANATION OF PLATE III. 
Fig. 1. Polydora ( Leucodore ) ciliata, with ova, from a photomicrograph, 
highly magnified. Original. 
„ 2. Young larva) of Polydora from a photomicrograph, taken shortly 
after its escape from the ova-sac, highly magnified. Original. 
„ 3 & 4. Older stages, from a photomicrograph, highly magnified. 
Original. 
„ 5 to 9. Somewhat more advanced, after Prof. A. Agassiz. 
,, 10. Egg-cases of Polydora , attached to the side of the membranous 
tube, x 7 diameters. 
