[391] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 97 
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 Acalephe. 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 hydrothece 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 pedicies vary in length, and 
are often rather long and slender, especially the terminal ones. The 
gonothece 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 XX XVII, fig. 279) often oc- 
curs attached to the Fucus and other sea-weeds growing on the piies. 
The Halecium 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 XX XVIII, 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 2). 
The common, red branching sponge (p. 330) is frequent, and also 
a slender branching species of Chalina, near (. oculata. Two or more 
species of Tedania, forming irregular, massive, pale-yellow sponges of a 
brittle texture, are common. 
