INVERTEBKATE ANIMALS OF VINEYARD SOUND, ETC. 495 



the Leptochiton ruber, (p. 399, Plate XXV, fig. 166.) This adheres to 

 rocks and stones that are incrusted by the red nullipore IMhothamnion 

 polymorphum, with which its red color, of various shades, agrees very 

 closely. It is a far more abundant shell in the Bay of Fundy, where 

 it also lives among the same nullipore. Among the other less common 

 northern species, met with on these bottoms, are Bissoa exarata ; Lacuna 

 neritoidea ; and Astyris rosacea. 



Several very interesting species of naked mollusks (Nudibranchs) occur 

 on these bottoms, creeping over algae 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 arboresceutly-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 Eussell 

 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 papillae that cover its back. 



The JEolis papulosa 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 genimlata, 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 JDoto coronata, 

 (Plate XXV, fig. 170,) was associated with the Tergipes on the Obelia. 

 An undetermined species of JEolis, with bright red branchiae, 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 algae. 



Among the Ascidians there are several northern species, not before 

 found so far south. The Cynthia carnea (Plate XXXIII, 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 

 a thin 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 papulosa also occurred spar- 



