INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 391 



On the piles of Long Wharf, at New Haven, the Obelia gelatinosa of 

 Europe was found growing- in great luxuriance in September. The 

 water at this locality was quite brackish, but it will probably be found, 

 also, in pure sea- water, for on the coast of Europe it is common both 

 in brackish and pure ocean-water. It is probable that this species has 

 not been observed before on our coast, for although the name occurs 

 in several local lists, these refer, according to Mr. A. Agassiz, to other 

 species, and he does not include the present species in his Catalogue of 

 North American Acalephse. It is a large species, growing to the length 

 of ten or twelve inches, and branches widely and very profusely. It 

 differs from most of our other species in having a thick, compound 

 stem, composed of many united tubes. The smaller branches are, how- 

 ever, profusely divided, and the branchlets are simple, very slender, 

 white, and translucent, their delicacy contrasting strongly with the 

 stout, dark-colored stems. The larger branches mostly arise in pairs, 

 close together, but immediately diverge ; the small branches and branch- 

 lets are alternate. The hydrothecse are very small, deeply bell-shaped, 

 the rim divided into ten or twelve teeth, which are squarish in form, 

 and slightly emarginate at the end ; their pedicles vary in length, and 

 are often rather long and slender, especially the terminal ones. The 

 gonothecaB are elongated, urn-shaped, with a narrow, short, tubular 

 neck. I also found this species in April, growing on oysters, at Great 

 Egg Harbor, New Jersey. 



Several other species of Obelia occur in similar situations, together 

 with various related genera. 



The Sertularia pumila, (p. 327, Plate XXXVII, fig. 279) often oc- 

 curs attached to the Fucus and other sea- weeds growing on the piles. 



The Halecmm gracile V., (p. 328,) often grows on the piles in great 

 abundance, especially where the water is somewhat brackish, and it 

 sometimes also occurs in great profusion on floating drift-wood. 



Of Actinians the most frequent species is the Sagartia leucolena, 

 (p. 329, Plate XXXVIII, fig. 284,) which can almost always be found* 

 among the adhering barnacles and ascidians ; not unfrequently it at- 

 taches itself within a dead barnacle, and, in fact, seems quite partial to 

 such a location. 



The Metridium marginatum (p. 329) also frequently occurs on the 

 piles, but is much less frequent, and generally of smaller size than it 

 is farther north, as about Boston and on the coast of Maine. 



Several sponges occur frequently on the piles of the wharves, but 

 they have not been well determined. Among them the Grantia ciliata, 

 or a closely allied species, is very common, and also another of the same 

 group, which is tubular and branched, (Leucosolenia botryoides ?). 



The common, red branching sponge (p. 330) is frequent, and also 

 a slender branching species of Chalina, near C. oculata. Two or more 

 species of Tedania, forming irregular, massive, pale-yellow sponges of a 

 brittle texture, are common. 



