PELAGIC LARVAE OF NERINIDES AGILIS (VERRILL)

¹ Department of Zoology and Entomology, University of Connecticut, Storrs, Conn.
² The Marine Research Laboratory, Noank, Connecticut

Larvae of a spionid polychaete, occurring in the plankton of the Mystic River estuary from June through August, were isolated from plankton samples, photographed and drawn. Some of the isolated larvae were reared in the laboratory through metamorphosis and until the species was positively identified as Nerinides agilis (Verrill). Developmental stages of reared specimens agreed well with 3- to 17-setiger stages obtained from the plankton. Metamorphosis occurs at the 17- setiger stage. The 3-, 5-, 10-, 14- and 17-setiger stages are figured and pertinent larval characteristics described. The protrusible, acutely pointed prostomium, together with the deeply pigmented gut, are diagnostic features of all planktonic stages of this species.