INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 345 



bundles ; tlie two large tentacles (of which only one is drawn in the 

 figure) are usually folded backward between the red dorsal branchite, 

 which form a row along the back on each side. The other, S. rohiista 

 v., is a stouter species, which has much shorter seta^ in the dorsal fiisci- 

 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 iiUing 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 Seolecolepis virldis 

 V. This specieSj 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 branchi.e, 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 branchitB 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 branchine are bright red; the large tentacles are light 

 green, usually with a row of black dots, and often crossed bj" narrow 

 Hake-white lines or rings. This species has been found abundantly on 

 Naushou 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, Seolecolepis tenuis Y. 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 branchia^, red, often tinged with green, shorter than in the last. 

 The head is relatively broad, with the central lobe rounded in front. 

 The branchiae are coutiued to the anterior part of the body. The setie 

 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- 

 slmped 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 ciliatwn of Europe. It occurred in 

 large colonies, closely crowded together, building upright tubes in the 



