C AN

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CAN

It is the 4th constellation in the starry zodiac. See Astronomy.The reason generally assigned for its name as well as figure, is asupposed resemblance which the sun’s motion in this sign bearsto the crab. As the latter walks backwards, so the former, in this

i iart of his course, begins to go backwards, or recede from us.!y others, the disposition of stars in this sign is supposed to hgvegiven the first hint to the representation of a crab.

Cancer, Tropic of, in astronomy, a less circle of thesphere parallel to the equator, and passing through the beginningof the sign Cancer. See Astronomy.

Cancer, in medicine, a roundish, unequal, hard, and livid tu-mour, generally seated in the glandulous part of the body, sup-posed to be so called, because it appears at length with turgid veinsshooting out from it, so as to resemble, as it is thought, the figureof a crab-fish; or, others say, because, like that fish, where ithas once got, it is scarce possible to drive it away. See Medi-cine.

Cancer, in zoology, a genus of the class and order insectaaptera. l.egs eight in general, sometimes six or ten ; arms che-lated, two; eyes two, distant, in general foot-stalked, elongated,and moveable ; tail unarmed, jointed. Animals of this germs atparticular periods cast their shells, previously to which the limbsshrink, to facilitate their extrication. The "loss of a limb, withother animals irreparable, is of little consequence to these, as a fewweeks suffice to reproduce one: and in cases of bruise or mutila-tion, a consciousness of this eventual, and indeed speedy repro-duction, induces them violently to rid themselves of the injuredmember, and to await in seclusion the formation of a completesubstitute for it. Some species which are unprovided by naturewith any shelly covering, uniformly have recourse to such shellsas they find best accommodated to their purpose, and in whichtheir bodies are immersed, while their claws are protruded andunprotected. The correspondence of parts in both sides of almostall other animals is far from being universally observable in these.The claspcrs on one side are often of extraordinary size, and onthe other slender and small; and in some instances the large armis obliged to be supported by the back of the animal, both whilewalking and at rest, from its unwieldy and extravagant size. Thegenus comprehends an immense variety of species ; hut the chiefdivision is into the Brachvouri and Macrouri, or the short-tailedai) d the long-tailed: under the former of which the crab com-monly used in this country for food is the principal. It is foundchieif v oil the rocky coasts. Among the Macrouri, the commonlobster is the principal, and a well-known specimen. It inha-bits in the clearest water, and at the base of rocks which projectov er the sen. It is extremely prolific, depositing about 12,000*;ggs each time of laying. The warmth of summer is requiredffir maturing them. The C. Norwegicus, or Norwegian crab, isNaturally of a pale red colour, and variegated with yellow. It ismnger, and more slender than the ordinary lobster. For a re-presentation of it S'*e Plate VII. C. grapsus, or the streakedcr ab, is an inhabitant of the American and Indian seas. Its gene-]‘ a l pale yellow is finely interspersed with red streaks and spots,bee Plate VII.

k- horridvs, the horrid crab, with a projecting bifurcatedl"°iit, the end diverging ; body heart-shaped ; with tiie claws and;'S S covered with long and very sharp spines. It is a large species,and inhabits the rocks on the eastern coasts of Scotland . See‘ late N il.

k- stagnalis, is found generally in small shallow pools of rain7? tl -' r > and is very transparent. The head of the male is armed1 tangs • the tail of the female is furnished witli a bag of eggs atde base; See Plate V II. bb

k. lluRicoi.A, the land crab, or violet crab, with a smooth en-'re thorax, and the two last joints of the feet armed with spines,‘'inhabits the Bahama islands, as well as most lands between thetopics; and feeds upon vegetables. These animals live not onlym a kind of orderly society in the retreats in the mountains, but•‘gularly once a year march down to the sea-side in a body of|°nie millions at a time. As they multiply in great numbers,"A - choose the month of April or May to begin their expedition ;*f.. t * H>n sa % out by thousands from the stumps of hollow trees,°m the cletts of rocks, and from the holes which they dig for'Ptnstlves under the surface of the earth. At that time the w'holcS ound is covered with this band of adventurers; these is no set-

ting down one’s fool without treading upon them. The sea istheir place of destination, and to that they direct their march withright-lined precision. No geometrician could send them to theirdestined station by a shorter course; they neither turn to thelight nor left, whatever obstacles intervene; and even if they meetwith a house, they will attempt to scale the walls to keep the’un-broken tenor of their way. But though this-be the general orderof their route, they, upon other occasions, are obliged to conformto the face of the country; and if it i^ intersected noth rivers, theyare then seen to wind along the course of the stream. The pro-cession sets forward from the mountains with the regularity of anarmy under an experienced commander. They are commonlydivided into three battalions; of which the first consists of thestrongest and boldest males, who, like pioneers, march forward toclear the route and face the greatest dangers. They are oftenobliged to halt for w ant of rain, and to go into the most convenientencampment till the weather changes. The main body of thearmy is composed of females, w hich never leave the mountains tillthe rain is set iu for some time, and then descend in regular bat-talia, being formed into columns of 50 paces broad, and threemiles deep, and so close that they almost cover the gTound. Therear-guard follows three or four "days after; a straggling undisci-plined tribe, consisting of males and females, but not so vigorousas the former. The night is their chief time of proceeding; butif it rains by day, they do not fail to profit by the. occasion ; andthey continue to move forward in their slow- uniform manner. Whenthe sun shines and is hot upon the surface of the ground, theymake an universal halt, and wait till the cool of the evening.When they are terrified, they march back in a confused disorderlymanner, holding up their nippers, w ith which they sometimes tearoll'a piece of the skin, and then leave the weapon where they in-flicted the wound. They even try to intimidate their enemies;for they often clatter their nippers together, as if to threaten thosethat disturb them. But though they thus strive to he formidableto man, they are much more so to "each other; for they are pos-sessed of one most unsocial property, which is, that if any of themby accident is maimed in such a manner as to be incapable of pro-ceeding, the rest fall upon and devour it on the spot, and then pur-sue their journey. When after a fatiguing march, and escaping athousand dangers, (for they are sometimes three months in gettingto the shore,) they have arrived at their destined port, they pre-pare to cast their spawn. The peas are as yet within their bodies,and not excluded, as is usual in animals of this kind, under the tail;for the creature w aits for the benefit of sea w ater to help the deli-very. It has no sooner reached the shore, than it goes to theedge of the water, and lets the waves wash over its bodv two orthree times. This seems only a preparation for bringing the spaw uto maturity; for, without farther delay, they withdraw to seek a,lodging upon land: in the mean time the spawn grows larger, iiexcluded out of the body, and sticks to the barbes under the flap,or more properly the tail. This bunch is seen as big as a hen’segg, and exactly resembling the roes of herrings. In this state ofpregnancy they once more seek the shore for the last time; andslinking off their spawn into the water, leave accident to bring itto maturity. At this time whole shoals of hungry fish are at theshore in expectation of this annual supply; the sea to a great di-stance seems black witli them ; and about two thirds of the crabseggs are immediately devoured by these rapacious invaders. Th*eggs that escape are hatched under the sand; and, soon after, mil-lions at a time of these little crabs are seen quitting the slmre, andslowly travelling up to the mountains. The old - ones, however,are not sd active to return ; they have become so feeble and lean*that they can hardly creep along, and the flesh at that time changesits colour. Most of them, therefore, are obliged to continue iathe licit parts of the country till they recover, making holes inthe earth, which they cover at the mouth with leaves and dirt,that no air may enter, There they throw oil' their old shells,which they leave quite whole ; the place w here tliev opened onthe belly being unseen. At that time they are quite "naked, andalmost without motion for six days together, when they becomeso fat as to he delicious food. They have then under their sto-machs four large white stones, which gradually decrease in pro-portion as the shell hardens, aud, when they come to perfection,are not to be found. It is at tiiat time that the animal is seenslowly making its wav back; which is commonly performed in

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