EXPLANATION OF PLATE XVII. 



FiGUiiK 8C). — Potamilla oculifera, (p. 617;) in its tube, witli branchifc fnlly expanded, 

 from a living specimen, found at Eastport, Maine. 

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

 87a. — Tlie same ; bead and braucbia', dorsal view. 

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

 88rt. — Tbe same ; view of tbo operculum and tentacles, from above. 



(Figures Si, 88, 83« were drawn from nature, by J. IT. Emerton ; 87, 8~a by A. E. Verrill.) 



