INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 305 



this region is probably more imperfectly known than that of other kinds 

 of bottom. This is mainly owing to the difiiculties 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, &c., in this region. 



The common crab, Cancer irroratns, (p. 312,) Panopeus Sayi, (p. 312,) 

 P. dejyressus, (p. 312,) the larger hermit-crab, Eupagurus poUicaris, (p. 

 313,) and the smaller hermit, -E7. longicarpus,{\). 313,) are common species 

 on the rocky bottoms. A small species of spider-crab, Pelia mutica^ oc- 

 casionally occurs. The Cancer borealls 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, Homarns Americanns, 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 larvte of the lobster, in 

 tlie 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 an inch 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 donlitless 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 

 III, fig. 10,) another quite different species [Hippolyte pusiola) was often 

 met with on the rocky bottoms. This is a smaller species, about an inch 

 long, of a i)ale 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 bauds of red or white; the antenna^, are annulated 

 with flesh-color and light red, and the legs are sometimes specked with 



