INVERTEBRATE ANIMALS OF VINEYARD SOUND, ET '. 349 



similar places. But the worms are very uulike in appearance and 

 structure. 



Several species of slender, greenisli worms, belonging to the gen- 

 era, Fhyllodoce, Eumidia, UulaUa^ and -Efeone, are occasionally dugout of 

 the sand. In all these the head is well-developed and prov ided with 

 four antemicv at the end, and in the three last with an odd median 

 one on its upper side, and they all have two well-developed eyes, 

 and oval or lanceolate, leaf-like branchine along the sides of the back. 

 They are ver-y active species, and most of them belong properly to 

 the shelly and rocky bottoms in deeper water, where they are often 

 very abundant. In sheltered coves, where there is mud with the sand, 

 Cistenides Goiddii V., (p. 323, Plate XVII, figs. 87, 87a,) often occurs, 

 but it is more partial to the muddy shores. On various dead shells, as 

 well as on certain living ones, and on the back of Limulus, &c., the 

 masses of hard, sandy tubes, built and occupied by the ^abellaria vul- 

 garis v., (p. 321, Plate XYII, figs. 88, 88«,) often occur. 



Of the Xemerteans the largest and most conspicuous is the 2Ieclcelia 

 ingens (]). 324, Plate XIX, figs. 90, 9Ga.) This species lives in the 

 clear sand, near low-water mark, as well as in places that are more or 

 less muddy, and notwithstanding its softness and fragility, by its means 

 of burrowing rapidly, it can maintain itself even on exposed shores, 

 where the sands are loose and constantly moved by the waves. The 

 young, several inches or even a foot in length, are quite common, but 

 the full-grown ones are only occasionally met with. The largest that I 

 have found were at least 15 feet long, when extended, and over an inch 

 broad, being quite flat; but they co ild contract to two or three feet in 

 length, atiil then became nearly cylindrical and about three-quarters 

 of an inch in diameter ; the body was largest anteriorly, tapering very 

 gradually to the posterior end, which was flat and thin, terminated by 

 a central, small, slender, acute, contractile process one-quarter of an 

 inch or less in length. The proboscis of the largest one, when pro- 

 truded, was fifteen inches long, and about one-fifth of an inch in diame- 

 ter where thickest. This proboscis, which is forcibly protruded from a 

 terminal opening in the head, appears to be an organ of locomotion, at 

 least to a certain extent, for when it penetrates the loose sand in any 

 direction it makes an opening into which the head can be thrust, and 

 then, by enlarging the opening, it can easily penetrate. But the pro- 

 boscis is probably used, also, as an instrument for exploring the sand 

 in various directions, either in search of food or to test its hardness or 

 fitness for burrowing, thus economizing time and labor. At any rate, 

 the ways in which this remarkable instrument is used by these worms, 

 when kept in confinement with sand, suggest both these uses. But 

 the proboscis is by no means the principal organ of locomotion, for the 

 head itself is used for this purpose, urged forward by the undulatory 

 movements of the muscular body, and aided by the constantly chang- 

 ing bulbous expansions, both of the head and body, which both crowd 



