EXPLANATION OF PLATE XVII. 



FiGUiiE 80. — Potamilia oculifera, (p. 617;) in its tube, with 'brancliiai fully expanded, 

 from a living specimen, found at Eastport, Maine. 

 87.— Cistenides Gouldii, (p. 612;) lateral view. 

 87fl. — The same ; head and branchiiB, dorsal view. 

 88. — Sabellaria vulgaris, (p. 611;) lateral view. 

 88a. — The same ; view of the operculum and tentacles, from above. 



(Figures 84, 88, 83a were drawn from nature, by J. H. Emerton ; 87, 87a by A. E. Veriill.) 



