{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 
are as follows: line 80, a, 164 fathoms, siliceous sand; b, 184 fathoms, 
siliceous sand; 81, a, b, 164 fathoms, sand; 85, a, b, 154 fathoms, sili- 
ceous sand and gravel; 86, a, b, 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; Hupagurus Bernhardus, a decidedly 
northern hermit crab; Crangon vulgaris, (p. 339, Plate IIT, fig. 105) 
Ptilocheirus pinguis ; Idotea Tuftsti. Where the bottom is of loose 
siliceous sand, the common Unciola irrorata (p. 340, Plate IV, 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 mere 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 Kroyer, 
which is a northern species; Siphonecetes cuspidatus SMITH, an undes- 
cribed species; Byblis 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 V., (p. 348 ;) Lumbriconereis fragilis, a 
northern and European species; Anthostoma acutum V.; 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. 
