INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 313 



higher up toward high-water mark, and is comparatively rare. This is 

 the Panopeus Harrlsii. It can be easily distinguished, for it lacks the 

 black on the ends of the big claws and has a groove along the edge of 

 the front ofi the carapax, between the eyes. This last species is also 

 found in the salt marshes, and was originally discovered on the marshes 

 of the Charles Eiver, near Boston. All the species of Panopeus are south- 

 ern forms, extending to Florida, or to the gulf-coast of the Southern 

 States, but they are rare north of Cape Cod, and not found at all on 

 the coast of Maine. They contribute largely to the food of the tautog 

 and other fishes. The lobster, Homarus Americanus, is sometimes found 

 lurking under large rocks at low-water, but less commonly here than 

 farther north, as, for instance, about the Bay of Fundy. In this region 

 it lives also on sandy and gravelly bottoms, off shore, but in rather 

 shallow water. It is an article of food for many fishes, as well as for 

 man. Active and interesting little "hermit-crabs," Uupagurus longi- 

 carpus, /are generally abundant in the pools near low- water, and con- 

 cealed in wet places beneath rocks. In the pools they may be seen 

 actively running about, carrying upon their backs the dead shell of 

 some small gastropod, most commonly Anacliis avara or Ilyanassa 

 obsoleta, though all the small spiral shells are used in this way. They 

 are very pugnacious and nearly always ready for a fight when two 

 happen to meet, but they are also great cowards, and very likely each, 

 after the first onset, will instantly retreat into his shell, closing the 

 aperture closely with the large claws. They use their long slender 

 antennce very efficiently as organs of feeling, and show great wariness 

 in all their actions. The hinder part of the body is soft, with a thin 

 skin, and one-sided in structure, so as to fit into the borrowed shells, 

 while near the end there are appendages which are formed into hook- 

 like organs by which they hold themselves securely in their houses, for 

 these spiral shells serve them both for shields and dwellings. This 

 species also occurs in vast numbers among the eel-grass, both in the 

 estuaries and in the sounds and bays, and is also frequent on nearly all 

 other kinds of bottoms in the sounds. It is a favorite article of food 

 for many of the fishes, for they swallow it shell and all. A much 

 larger species, belonging to the same genus, but having much shorter 

 and thicker claws, {Enpagurus poll'icaris,) is also found occasionally under 

 the rocks at low-water, but it is much more common on rocky and shelly 

 bottoms in the sounds and bays. Its habits are otherwise similar to the 

 small one, but it occupies much larger shells, such as those of Lunatia 

 heros, Fulgur cariea, &c. This large species is devoured by the sharks 

 and sting-rays. 



The Amphipods are also well represented on the. rocky shores by 

 a considerable number of "species, some of which usually occur in 

 vast numbers. These small Crustacea are of great importance in con- 

 nection with our fisheries, for we have found that they, together with the 

 shrimps, constitute a very large p art of the food of most of our more valu- 



