[495] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 201 
the Leptochiton ruber, (p. 399, Plate XXV, fig. 166.) This adheres to 
rocks and stones that are incrusted by the red nullipore Lithothamnion 
polymorphum, with which its red color, of various shades, agrees very 
closely. It isa far more abundant shell in the Bay of Fundy, where 
it alsolives among the same nullipore. Among the other less common 
northern species, met with on these bottoms, are Risso exarata ; Lacuna 
neritoidea ; and Astyris rosacea. 
Several very interesting species of naked mollusks (Nudibranchs) occur 
on these bottoms, creeping over alge and hydroids, and feeding upon 
the latter. One of the most conspicuous of these is the Dendronotus 
arborescens, which is a northern form, and had not been found south of 
Cape Cod until this spring, when we dredged it on the reef off Watch 
Hill, in four or five fathoms. It can be easily distinguished by the two 
rows of large arborescently-branched gills along the back; by the 
branched lobes of the tentacle-sheaths and the arborescently divided 
branch on their outer side, near the base; and by the very narrow and 
almost linear foot, which is adapted for creeping over hydroids. 
The. Onchydoris pallida was dredged by Messrs. Prudden and Russell, 
off Cuttyhunk Island, in April, 1872. It has not been previously re- 
corded from south of Cape Cod, but it is common in the Bay of Fundy. 
It can easily be recognized by its pale yellow color, and the long, blunt- 
conical papille that cover its back. 
The Holis papillosa and Tergipes despectus were both found at Watch 
Hill this spring, April 13, and are new additions to the fauna of south- 
ern New England. The former was found, with its eggs, among the 
roots of Laminaria; the latter was abundant in four or five fathoms, 
creeping over Obelia geniculata, which was abundant on the fronds of 
Laminaria. Its eggs, inclosed in small masses of gelatinous matter 
were attached to the Obelia in large numbers. The Doto coronata, 
(Plate XXV, fig. 170,) was associated with the Tergipes on the Obelia. 
An undetermined species of Molis, with bright red branchiz, was 
dredged off Gay Head, on a rocky bottom. 
The Lamellibranchs are not of much interest, and scarcely any are 
peculiar to this kind of bottom. The Modiola modiolus (p. 309, Plate 
XXXI, fig. 237) is one of the most common and characteristic species. 
The northern scaly or spiny Anomia aculeata (Plate XXXII, figs. 239, 
240) is common; it adheres to rocks, shells, and the roots and stems 
of large alge. 
Among the Ascidians there are several northern species, not before 
found so far south. The Cynthia carnea (Plate XX XIII, figs. 247,248) was 
found off Gay Head in ten fathoms. The young specimens were numer- 
ous on the stones and shells. In contraction they are low and flat, with 
athin margin; the color is light red, or flesh-color. With this a few 
young specimens of Cynthia echinata were found. These are peculiar in 
being covered by stellate spines. The color of the young specimens is. 
pink, the apertures rose-red. The Molgula papillosa also occurred spar- 
