INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 319 



males. The males, however, sometimes occur swimmiu;;' free at the 

 surface in vast numbers. They swim with an undulating motion, and 

 are quite conspicuous on account of the bright red color of the middle 

 region of their bodies. Mr. S. I. Smith observed them swimming in 

 this way, in the daytime, in August, at Fire Island, on the southern 

 side of Long Island, where they occurred in incredible numbers and 

 were eagerly pursued by the blue fish, which at such times would not 

 take bait. We often caught them in Vineyard Sound, in the evening, 

 at the surface, with towing-nets. These worms must, therefore, con- 

 tribute largely to the food of many fishes. It is very common on our 

 sandy shores as far south as South Carolina. A third species. Nereis 

 pclagica. (Plate XI, figs. 52-55,) is abundant under stones farther nortb, 

 but in this region is chiefly found on shelly bottoms, in the deeper wa- 

 ters of the sounds. These three species of Nereis are called " clam- 

 worms" by the fishermen. Two large species of worms belonging to 

 the genus Rhynchobolus (formerly Glycera) are often met with in bur- 

 rows, in the mud beneath stones. These are pale reddish, deep fiesh- 

 colored, or dull purplish red, and rather smooth-looking worms, thick- 

 est in the middle, and tapering to both ends. They have a large pro- 

 boscis, armed at the ends with four black, hook-like jaws, and are re- 

 markable* for their rapid spiral gyrations. They belong more properly 

 to the muddy and sandy shores, and will, therefore, be mentioned more 

 particularly in another place. They are represented on Plate X, figs. 

 43-4G. Oplielia simjilex occurs under stones at half-tide, and below. 



The Marphjsa Leidyi (Plate XII, fig. G4) is a large and handsome 

 worm, occasionally met with under stones at low-water mark, but is 

 more common on shelly bottoms in shallow water off shore. It grows 

 to the length of six inches or more, and its body is flattened, except 

 toward the head, where it becomes much narrowed and nearly cylin- 

 drical. It is yellowish or brownish red, and brilliantly iridescent. The 

 branchia? are bright red, and commence at about the sixteenth segment ; 

 the first ones have only one or two branches, but farther back they be- 

 come beautifully pectinated. There are six unequal caudal cirri, the 

 lower lateral ones longest. It is furnished with powerful jaws, and is 

 carnivorous in its habits. 



A small but very active worm, Podarlxe ohscura V., (Plate XII, fig. 61,) 

 is often found in large numbers beneath stones. These are dark brown 

 or blackish in color, sometimes with lighter bands. They come out at 

 night and swim at the surface in vast numbers. They are also often met 

 with at the surface among eel-grass, in the daytime, in large numbers. 

 A large and very singular worm, which burrows and constructs tubes 

 in the mud and gravel beneath stones, is the Cirratulus grandis V., 

 (Plate XV, figs. 80, 81.) This is usually yellowish brown, dull orange, or 

 ocher-colored, and is remarkable for the numerous long, flexible, reddish 

 or orange cirri that arise all along the sides. Another very large and 

 interesting worm, often associated with the last, both among and under 



