[845]. INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 51 
bundles; the two large tentacles (of which only one is drawn in the 
figure) are usually folded backward between the red dorsal branchiz, 
which form a row along the back on each side. The other, S. robusta 
V., is a stouter species, which has much shorter sete in the dorsal fasci- 
cles; the middle lobe of the head is emarginate in front and the lateral 
lobes are convex. Both species have four small eyes on the top of the 
head, those of the posterior pair nearest together. In similar places, 
and often associated with the two preceding species, another allied 
worm often occurs in great abundance, completely filling the sand, in 
its chosen abodes, with its round vertical holes, and throwing out cylin- 
ders of mud. It is so gregarious that in certain spots hundreds may be 
found within a square foot, but yet a few yards away, on the same kind 
of ground, none whatever may be found. This is Scolecolepis viridis 
V. This species, like the two preceeding, has a pair of large tentacles 
on the back part of the head, which are usually recurved over the back 
between the rows of ligulate branchie, and four eyes on the top of the 
head ; the central lobe of the head is slightly bilobed in front, the lateral 
ones convex; the branchiz are long, slender, ligulate, meeting over the 
back, and exist only on about one hundred segments, or on about the 
anterior third part of the body. The body is rather slender, depressed, 
and about three inches long when full grown. The color is usually dark 
green, or olive-green, but sometimes light green, or tinged with reddish 
anteriorly; the branchiz are bright red; the large tentacles are light 
green, usually with a row of black dots, and often crossed by narrow 
flake-white lines or rings. This species has been found abundantly on 
Naushon Island, and other localities in that region; at New Haven; and 
at Somer’s Point and Beesley’s Point, New Jersey. With the last species 
at Great Egg Harbor, New Jersey, another more slender species of the 
same genus occurred, Scolecolepis tenuis V. This was three or four 
inches long and very slender; the body was pale green; the tentacles 
longer and more slender than in the last, whitish, with a red central 
line; the branchiz red, often tinged with green, shorter than in the last. 
The head is relatively broad, with the central lobe rounded in front. 
The branchie are confined to the anterior part of the body. The sete 
in the upper fascicles are much longer than in the last species, those of 
the three anterior segments longer than the others and forming fan- 
shaped fascicles, directed upward and somewhat forward. 
Another singular Annelid, belonging to the same tribe and having 
nearly the same habits, is represented in Plate XIV, fig. 78, this has 
been found by Mr. A. Agassiz burrowing in sandy mud at about half- 
tide, both at Naushon Island and at Nahant, Massachusetts, and he has 
also described its development and metamorphoses, but I have not met 
with the adult myself in this region, although the young were frequently 
taken in the towing-nets in the evening. Mr. Agassiz regards it as 
perhaps identical with Polydora ciliatum of Europe. It occurred in 
large colonies, closely crowded together, building upright tubes in the 
