[431] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 137 



length and breadth, though small areas of rocks, gravel, and sand occur 

 at various places. 



The special localities, indicated on the chart, where dredgings were 

 made on muddy bettoms, not including the outside dn-dgiiigs, are as 

 follows : In Buzzard's Bay, at line 67, b ; 68, a, &, c : 74, , b ; 75, a, &, 

 c, <?, e, /; in Hartley Harbor, at 10, a, &, c, d ; in Great Harbor, at 17, 

 &, c; 19, b ; in JRobinson's Hole, at 78, a, &, c ; in Vineyard Sound, at 

 47, &, c. Numerous other dredgings were made on muddy bottoms in 

 this region that are not indicated on the chart. 



In Long Island Sound numerous dredgings have been made by the 

 writer, with Mr. S. I. Smith and others, during eight years. These ex- 

 tend from a few miles west of the entrance of New Haven Harbor to 

 the Thimble Islands and Faulkner's Island on the east ; and from the Con- 

 necticut shore nearly across the sound. The greater part of these dredg- 

 ings were on muddy bottoms, and generally in 3 to 8 fathoms of water. 



The following are some of the most common and important of the 

 Crustacea living on these mudd}^ bottoms : the spider crab, Libinia can- 

 aliculata, (p. 368,) L. dubia, (p. 368,) Panopeus depressus, (p. 312, Plate 

 I, fig. 3,) P. Sayi, (p. 312,) the " blue-crab," Callinectes hastatus, (p. 367,) 

 Mysis Americana, (p. 396,) Ptilocheirus pinguis, (p. 431,) Unciola irro- 

 rata, (p. 340, Plate IV, fig. 19,) Limulus Polyphemus, (p. 340.) Numer- 

 ous tube-dwelling Amphipods, including several species of Ampelisca 

 and genera belonging to the Lysianassince occur, some of them in great 

 numbers, and also additional species of crabs and shrimps. All these 

 are of special importance, because they furnish great quantities of food 

 for the fishes frequenting muddy bottoms. 



Of Annelids numerous burrowing and tube-dwelling kinds are to be 

 found, some of them in great abundance. One of the most abundant 

 and conspicuous species is Nephthys ingens, (Plate XII, figs. 59, 60.) This 

 worm burrows in mud of all kinds, even in that which is so filled with 

 decaying vegetable debris as to be very fetid. It grows to the length 

 of more than six inches, with a diameter of a quarter of an inch or more, 

 though most of the specimens are about half this size. The body is 

 whitish, with a red median blood-vessel, but the lateral appendages are 

 ,dark and the setae nearly black. It is very active, and wriggles about 

 energetically by undulating its body laterally, to the right and left ; this 

 motion enables it to burrow quickly, or to swim quite rapidly. When 

 captured it is very apt to break off the posterior part of its body, 

 but can reproduce it. 



The Diopatra cuprea (p. 346, Plate XIII, figs. 67, 68) is often abun- 

 dant where the mud is somewhat firm ; the dredge often brings up large 

 quantities of the projecting ends of its large tubes, but the occupant 

 usually escapes by retreating below the surface. The two species of 

 Ehynchobolus are also quite common, but R. dibranchiatus (p. 341, Plate 

 X, figs. 43, 44) is generally the most abundant. The curious 7'wmw 

 earned V. is seldom met with, and, like Brada setosa V., appears to be rare 



