[395] INVERTEBRATE ANIMALS OF VINEYARD ,SOUND ETC. 101 
this region is probably more imperfectly known than that of other kinds 
of bottom. This is mainly owing to the difficulties encountered in 
dredging upon rough rocks. 
Rocky bottoms are very favorable for many kinds of Crustacea, both 
for those that swim free and conceal themselves among the sea-weeds 
that grow on rocks in shallow water, and for those that take refuge be- 
neath the rocks. Consequently rocky bottoms are the favorite feeding- 
grounds for certain kinds of fish, especially tautog, striped bass, black 
bass, cunners, &e., in this region. 
The common crab, Cancer irroratus, (p. 312,) Panopeus Sayi, (p. 312,) 
P. depressus, (p. 312,) the larger hermit-crab, Hupagurus pollicaris, (p. 
313,) and the smaller hermit, 2. longicarpus, (p. 313,) are common species 
on the rocky bottoms. A small species of spider-crab, Pelia mutica, oc- 
casionally occurs. The Cancer borealis has hitherto been a rare species, 
and little is known concerning its habits or distribution ; it appears to 
frequent rocky bottoms chiefly, but most of the specimens obtained in 
this region were found thrown up by the waves on the shores of Cutty- 
hunk Island, No Man’s Land, and near Gay Head. 
The lobster, Homarus Amerjcanus, frequents rocky bottoms, concealing 
itself under and among the rocks while watching for its prey, but it is 
much less abundant in this region than on the coast of Maine and in the 
Bay of Fundy, and does not usually grow to so large a size as in the 
northern waters. It also occurs on the sandy and gravelly bottoms of 
Vineyard Sound, where most of those sent to the markets from this re- 
gion are obtained. The young, free-swimming larvee of the lobster, in 
the stages represented in Plate IX, figs. 38, 39, were often taken at the 
surface in great abundance, during June and July, in the towing-nets. 
The young lobsters were also found swimming actively at the surface 
by Mr. S. I. Smith, even after they had acquired the true lobster-like 
form and structure, and were nearly three-quarters of aninch long. In 
this stage they swim and act much like shrimp. While young, there- 
fore, the lobster must be devoured in immense numbers by many kinds 
of fishes, and even when of considerable size they are still preyed upon 
by the tautog and black bass, and especially by sharks, skates, and rays, 
and doubtless by other fishes. We found the lobsters very abundant 
off Menemsha on a sandy and weedy bottom in shallow water. At this 
place over one hundred were taken at a single haul, by the trawl. The 
lobsters caught for the market are nearly all caught in “ lobster-pots,” 
baited with refuse fish of various kinds. 
In addition to the common shrimp, Crangon vulgaris, (p. 339, Plate 
ILI, fig. 10,) another quite different species (Hippolyte pusiola) was often 
met with on the rocky bottoms. This isa smaller species, about an inch 
long, of a pale gray, salmon, or flesh-color, often specked with red ; 
there is usually a white stripe along the middle of the back, and some- 
times transverse bands of red or white; the antennie are annulated 
with flesh-color and light red, and the legs are sometimes specked with 
