[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 a light 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, Kew 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 Kiver, near Boston. Watch Hill, Rhode Island, and Brook 

 lyn, New York (D. 0. Eaton). 



AMARCECIUM PELLUCIDUM Yerrill. (p. 401.) 



Amouroucium pellucidnm Verrill, Amer. Jour. Science, ser. iii, vol. i, p. 290, 1871 ; 

 vol. iii, 13. 211. Alcyomdium f pellnddum 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 

 more or less convex, usually with a single central cloacal orifice, sur 

 rounded by an irregular circle of individual zooids, 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 mm to 25 mm 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 

 lae ; 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 truncated 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 



