POLYCERA QUADRILINEATA. 



This is rather a lively animal, and is fond of swimming in the usual inverted position. 

 It will sometimes suspend itself from the surface by its tail, which it forms into a kind of 

 cup for the purpose. 



The spicula are few and rather small. They are nearly of uniform width, bent in the 

 middle and rounded at the ends, and are more or less covered with warty tubercles. The 

 heart beats from ninety to a hundred times in a minute. 



Figs. I, 2. Polycera quadrilineata, different views. 



3. The same, a black-banded variety. 



4, 5. A tentacle, profile and front views. 



6, 7. A branchial plume, two views. 



8. Spicula. 



9. The spawn. 



10. A portion of the same more highly magnified. 



11. The larva. 



