[703] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 409 
tissue, the enlarged ends appearing as oval or pyriform spots, lighter 
than the ground-color. The branchial openings are small and circular, 
surrounded by alight halo. The animals differ considerably in form, 
according to the state of contraction. 
The color is extremely variable; several of the color-varieties have 
been named and described on pages 375, 376. 
Brooklyn, New York, to Boston, Massachusetts. Very abundant at 
Wood’s Hole, Waquoit Pond, and other similar localities along the 
shores of Vineyard Sound and Buzzard’s Bay; abundant at the mouth 
of Charles River, near Boston. Watch Hill, Rhode Island, and Brook- 
lyn, New York (D. C. Eaton). 
AMARGCIUM PELLUCIDUM Verrill. (p. 401.) 
Amouroucium pellucidum Verrill, Amer. Jour. Science, ser. iii, vol. i, p. 290, 1871; 
vol. ili, p. 211. Aleyonidium ? pellucidum Leidy, Jour. Acad. Nat. Science, 
Philad., ser. ii, vol. iii, 1855, p. 142, Plate 10, fig. 25, (mutilated zooid). 
Colonies large, complex, consisting of a large number of small, elong- 
ated, clavate colonies, arising from a common base, and more or less 
separate laterally and at summit, thus forming large aggregated hemi- 
spherical or irregular masses, often six inches in diameter, the surface 
generally covered thickly with adhering sand, but frequently naked 
over the summits of the colonies, or even over large surfaces of the 
masses, when, as often happens, the central colonies coalesce; when 
naked, the tissue is smooth, translucent, gelatinous-looking, and soft. 
The small side-colonies are long, with a slender stolon-like base, curv- 
ing outward and ascending, enlarging gradually to the summit, which is 
mere or less convex, usually with a single central cloacal orifice, sur- 
rounded by an irregular circle of individual zodids, varying in number 
according to the size or age of the colony to which they belong. The 
zooids, when mature, are long and slender, varying greatly in length in 
each colony, according to the state of development of the post-abdomen; 
the largest are often 20°" to 25" in length. The stomach is bright 
orange-red, and quite conspicuous; the slender post-abdomen exceeds 
in length the rest of the body, but is not more than half the diameter 
of the thorax, and is slightly constricted at base. In young individuals, 
not half grown, the post-abdomen forms nearly half the whole length, 
and is very slender. The branchial aperture has six, short, round papil- 
le; the anal is situated a short distance from the end of the body, and 
has short inconspicuous lower lobes, with an elongated, pointed lobe 
above. The branchial sac is oblong, with numerous longitudinal and 
transverse vessels and a broad ventral duct. The stomach is about as 
broad as long, subglobular, with the ends truneated and the surface 
covered with numerous, interrupted, longitudinal, glandular ridges. 
The post-abdomen is nearly filled by the large, elongated ovary, which 
extends nearly to the posterior end on the dorsal or atrial side, and con- 
tains numerous closely-packed ovules of comparatively large size, and 
