426 EEPORT OF^DMMISSIONEE OF FISH AND FISHERIES. 



rowing' beneath the surface of the sand, though many of them may also 

 occur creeping on its surface. 



The most abundant and cliaracteristic species of Crustacea are the lob- 

 ster, Homarus AmericamtSj (p, 313,)*the common shrimp, Crangon vul- 

 garis, (p. 330, Plate III, fig. 10,) the "lady-crab," PJaUjoniclms ocellatns, 

 (p. 338, Plate I, fig. 4,) the larger hermit-crab, Eupagurus pollicaris, (p. 

 313,) the smaller hermit-crab, JEupagnrns longicarpus, (p. 313,) Anthura 

 hrunnea, Conilerh concharum, Unciola irrorata, (p. 310, Plate IV, fig. 19.) 



Of Annelids a considerable number of burrowing species occur, and 

 also a few tube-dwelling species, which attach their tubes to dead shells ; 

 among these last are Sabellaria vulgaris (p. 321, Plate XVII, figs. 88, 88rt,) 

 and Serpula dianthus, (p. 322.) 



The Gastropods are not numerous, and but few are jjeculiar to sandy 

 bottoms; the majority found have their proper homes on shelly or 

 muddy bottoms and live in much smaller numbers in sandy places; 

 others enumerated in the following list inhabit the patches of eel-grass 

 and algte that are often scattered over the sandy bottoms in shallow 

 water. A few species, however, have their i^roper homes on the sandy 

 bottoms. Among the most important of these are Lunatia heros, (p. 353, 

 Plate XXIII, tigs. 133-136,) Neverita duplicata, (p. 351, Plate XXIII, fig. 

 130,) Natica pusilla, (p. 351, Plate XXIII, fig. 132,) CyUchna oryza, 

 (Plate XXV, tig. 161,) JJtriculus canaliculatus, (Plate XXV, fig. 160.) 



The bivalve shells are more numerous, and most of them are species 

 that burrow beneath the surface. The most common and characteristic 

 species are Ensatella Americana, (p. 356, Plate XXVI, fig. 182, and 

 Plate XXXII, fig. 245,) Biliqua costata, (p. 358, Plate XXXII, fig. 214,) 

 Mactra soUdissimaj (p. 358, Plate XXVIII, tig. 202,) Angulus tener, (p. 

 358, Plate XXVI, fig. 180, and Plate XXX, 223, shell;) Tottenia gemma, 

 (p. 359, Plate XXX, fig. 220,) Lyonsia hyalina, (p. 358, Plate XXVII, fig. 

 194.) In certain localities, where eel-grass grows, the scollop, Pecten 

 irradians, (p. 361, Plate XXXII, fig. 243,) occurs in considerable abun- 

 dance. The common muscle, Mytihis edulis, (Plate XXI, fig. 234,) occa- 

 sionally occurs in patches or beds. La'vicardium Mortoni (p. 358, Plate 

 XXIX, fig. 208) IS sometimes abundant in sheltered localities. The 

 Ceronia arctata api)ears to be abundant in some places, as it is some- 

 times thrown on the sandy beaches in large numbers, but it was seldom 

 dredged. The Thracia Conradi lives on sandy bottoms, buried six 

 inches or more beneath the surface, but is seldom obtained alive. The 

 dead shells were occasionally dredged in Vineyard Sound. 



Very few Ascidians occur. The most frequent one is Molgula arenata, 

 (p. 419, Plate XXXIII, fig. 251,) which lives free in the sand and covers 

 itself with a coating of closely adherent grains of sand. Another species, 

 M.pellucida, is occasionally met with ; this also lives free in the sand, but 

 does not attach the sand to itself. It has a clean translucent integu- 

 ment, a round body, and two tubes which are large and swollen at their 



