INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 703 



tissue, tlie enlarged ends appearing as oval or pyriforin spots, lighter 

 tha 1 fii<^ urouud-rolor. The branchial opeuiugs 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, New York, to Boston, Massachusetts. Very abundant at 

 Wood's H >;e, Waquoit Pond, and other similar localities along the 

 shores of Vineyard Sound and Buzzard's Bay ; abundant at the mouth 

 of Charles Eiver, near Boston. Watch Hill, Rhode Island, and Brook- 

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



Amarcecium pellucidum Verrill. (p. 401.) 



Amouroucium pellucidum Verrill, Amer. Jonr. Science, ser. iii, vol. i, p. 290, 1871 • 

 vol. iii, p. 211. Alcijomdhim f peUucidum 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, gelatiuous-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"™ to 25""' in length. The stomach is bright 

 orange red, and quite conspicuous; the sleuder 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 loug, sabglobular, 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 



