[501] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 207 



of animals, and especially for many burrowing annelids, Crustacea, and 

 bivalve shells. Bottoms of this character pass by insensible gradations 

 into the true muddy bottoms, so that it is very difficult to make any 

 sharp distinction between them, or between the animals that inhabit 

 them. Several localities at which we dredged were quite intermediate 

 in character, so that it is difficult to decide in which division they should 

 be put. Yet there is a very wide difference between the animals of the 

 pure sandy and of the soft muddy bottoms. Most of the localities where 

 the bottom was of this mixed or intermediate character, and of very fine 

 material, have been classed with the muddy bottoms, because the ani- 

 mals inhabiting them agree more closely with those of the true muddy 

 bottoms than with those of the genuine sandy ones. But in each case 

 I shall endeavor to give an idea of the fauna of typical localities of 

 pure sand, of true mud, of muddy sand, and of sandy mud, so that the 

 more general lists given under the sandy and muddy bottoms, respect- 

 ively, need not cause confusion. 



The special localities where dredgings were made on sandy bottoms 

 a*re as follows : line 80, a, 16J fathoms, siliceous sand ; &, 18J fathoms, 

 siliceous sand ; 81, a, ft, 16 J fathoms, sand ; 85, a, 6, 15 J fathoms, sili- 

 ceous sand and gravel ; 86, a, &, 25 fathoms, sand and gravel, with some 

 mud and small stones ; off Watch Hill, 6 to 8 fathoms, loose siliceous 

 sand, with some stones. Besides these a few other dredgings were made 

 on similar bottoms, but not recorded. 



Among the Crustacea that are characteristic of the true sandy bot- 

 toms are Platyonichus ocellatus, (p. 388, Plate I, fig. 4,) which is, how- 

 ever, more common in the sounds ; Eupagurus Bernhardus, a decidedly 

 northern hermit crab; Crangon vulgaris, (p. 339, Plate III, fig. 10;) 

 Ptilocheirus pinguis ; Idotea Tuftsii. Where the bottom is of loose 

 siliceous sand, the common Unciola irrorata (p. 340, Plate IY, fig. 19) 

 frequently occurs, usually associated with but few others, except a 

 species of Anonyx, or some closely allied genus, which seems to live 

 exclusively on such bottoms. This last species is rather stout, pale 

 grayish or yellowish white, usually tinged with purple on the back The 

 posterior portion is more decidedly purple, together with the caudal 

 appendages and some of the last epimera. This was dredged off Watch 

 Hill. 



Several interesting species occurred on the bottoms of fine compact 

 mud and sand, in 20-29 fathoms. Among these were Phoxus Kroyeri, 

 which is a northern species; Siphoncecetes cuspidatw SMITH, an undes- 

 cribed species ; ByUis serrata SMITH, another very interesting new 

 species ; undetermined species of Ampelisca, &c. 



Few Annelids are peculiar to true sandy bottoms. Among those of 

 most interest are Sthenelais picta Y., (p. 348;) Lumbriconereis fragilh, a 

 northern and European species ; Anthostoma acutum Y. ; and Scolecolepis 

 cirrata. The last is a northern species found in the Bay of Fundy and 

 north to the Arctic Ocean, and also on the northern coasts of Europe. 



