The article which is used in medicine called _crabs' claws_, consists of the black tips of the claws pounded, well washed in boiling water, and reduced to a fine powder. 264. _The LAND CRAB_ (Cancer ruricola) _is a crustaceous animal, common in some parts of America, the Bahamas, and other islands in the West Indies, which has a rounded shell without margin, and the first joints of the legs spinous, and the second and third furnished with tufts of hair._ _The shells of the largest land crabs are about six inches in diameter, and of various colours._ These crabs inhabit the clefts of rocks, the hollows of trees, or holes which they form in the ground. In the early part of the year they descend in myriads to the sea-coast, to deposit their eggs in the sand. They chiefly travel by night, but in rainy weather they also proceed during the day. The inhabitants of the countries where they abound are always eagerly on watch for their migrations towards the sea, and destroy immense numbers of them, disregarding, at this time, the bodies, and only taking out the spawn. It is on their return that the animals themselves are valuable as food. 265. _The LOBSTER_ (Cancer gammarus, Fig. 74) _is a well known crustaceous animal, distinguished by its long and jointed tail, its shell being smooth, and having betwixt the eyes a kind of beak toothed on each side, and with a double tooth at its base._ _These animals are of bluish black colour when alive, but, in boiling, this changes to a dingy red. They sometimes grow to an immense size._ _Lobsters are found among marine rocks in nearly all parts of Europe._ They are caught much in the same manner as crabs (263). The London markets are supplied with great numbers of lobsters from the Orkney Islands and the eastern parts of Scotland, and even from the coast of Norway. It is said that in London lobsters are sometimes boiled every day for a week or longer, to keep them sweet externally; but, notwithstanding this precaution, their inner parts become putrid. An immoderate use both of lobsters and crabs is sometimes attended with irruptions in the face, or a species of nettle rash over the whole body; and, when eaten in a state approaching to putrescence, they are sometimes productive of still more disagreeable effects.