The Life-History of Nucula delphinodonta (Mighels)

Abstract

The material upon which these observations were made was secured at Casco Bay, Maine, during the summers of 1897 and 1898. Nucula delphinodonta is a small form, seldom growing to be more than 4 mm. in length, and as it lives below low-tide mark it is not very well known by collectors. By using a sufficiently fine dredge, however, unlimited numbers of adult and young specimens may be procured. Individuals may be found living under very different conditions; in inlets and protected places, and exposed to the open sea, and from near low-tide mark to a depth of several fathoms. The principal habitat, however, is in the shallow inlets and near the heads of sounds, where the bottom is composed of fine mud, mixed with some sand, broken shells, and decaying vegetable matter. Individuals are most numerous just outside of the eel grass which skirts the shore where the bottom is of this character, in water which at low tide is from one to three fathoms deep. The mud in which they live is much like that inhabited by Yoldia limatula, except that it is not so free from shore débris. Although some specimens may be obtained where Yoldia is most abundant, they are generally more numerous somewhat nearer the shore, and they may be very numerous at considerable distances from places where Yoldia is known to thrive.