OCR Text |
Show 36 CHUSTACF.A. whose shells they are found, on friendly terms, warning them of danget• and seeking food for them. The inhabitants of certain districts, at the present day, attribute to theit• presence the unwholesome qualities sometimes manifested in the Mytili( 1 ). We now art'ive at Crustacea, which, although analogous to those just mentioned in the insertion of their ocular pedicles, are removed from them in respect to their shell. It is heart-shaped and truncated posteriorly, elevated, dilated and rounded on the sides near the anterior angles. The ocular pedicles are shorter than those of the preceding subgenera, and do not quite extend to the lateral extremities of the shell. The intermediate antennre are always terminated by two very distinct divisions. The inhabitants of the French colonies designate them by various appellations, such as, Toudouroux, Crabes-peints, Crabes de terre, and Crabes violets, which may apply to different species, or to varieties from age; no observations worthy of credence have as yet settled this point of nomenclature. These animals more particularly inhabit intertropical countries and those which adjoin them. Theit· habits are a constant source of interest to travellers, but by abstracting ft·om their accounts all improbable and doubtful facts, their history will be as follows. The greater porlion of their life is passed on land, where they secrete themselves in holes, from which they never issue but at night. Some inhabit cemeteries. Once in the year, about the spawning season, they collect in immense bands and pursue a direct course to the sea, heedless of all obstacles; after depositing their ova, they return much enfeebled. It is said that they seal up the mouth of their burrow during the time they are casting their shell. When this is effected, and while yet soft, they are called Boursiers, and their· flesh is much esteemed, although sometimes poisonous. This quality is attributed to the fruit of the manchineel, which they are supposed, falsely perhaps, to have eaten. In some of them, such as the UoA, Lat., The size of the feet, commencing witi1 those of the second pair, p.rogressivcly dim~rrishes; they are extremely pilose, and the tarsi lHmply sulcated Without any remarkable spines or dentations. . Th~ only species known-Cancer uca, L., Herbst., VI, 38, mhalnts the marshes of Guiana and of Brazil. In others, the third and fourth pair of feet are longer than the (1) For species see Leach, Malac. Pocloph. Britt., and Desmar., Consider. Gener. sur· les Crust., 116. DECAPOD A. 37 second and fifth; the tarsi are marked with dentated or very spinous ridges. They form two subgenera. CARDISOMA, Lat. The four antennre and all the joints of the external foot-jaws exposed; the three first joints of these same foot-jaws straight; the third shorter than the second, emarginated superiorly and nearly cordiform; the first of the lateral antennre almost similar and broad. They are called Crabes blanca at the Antilles, though sometimes they have a yellow shell striped with red(l ). GEcAROINus, Leach. The four antennre covered by the clypeus; second and third joints of the external foot-jaws, large, flattened, arcuated, and leaving a space between their inner sides, the last one forming a curvilinear triangle, obtuse at the summit; it reaches to the clypeus, and covers the three following ones, or the fourth, fifth, and sixth. The most common species-Cancer ruricola, L., Herbst., III, 36, when young, IV, xx, 116; xlix, I, is of a more or less lively blood-red colour, more or less extended, and sometimes spotted with yellow with a deeply marked impression of the letter H. It is the Crabe violet, and Crabe peint of travellers; the name of Tourlourou appears to me to be more peculiarly applied to this species(2). Sometimes the shell is nearly square, subisometrical or not, broader than it is long, flattened, and the front turned down for nearly the whole of its width. The ocular pedicles are short and inserted at the anterior lateral angles. The two ordinary divisions of the intermediate antennre are very distinct. The inner sides of the exterior foot-jaws are separated, leaving an angular space between them; their third joint is almost as long as it is broad. The (1} Cancer cordatus, L.;-Cancer earnifex, Herbst., XLI, 1, IV, 37;-C. guanltumi, Marcgrave. The tarsi have four ridges; there are two additional ones 1n the Gecarcini. (2) See the article Tourlourou in the Encyc. Methodique. Messrs Audouin and Edwards have lately communicated to the Acad. Uoy. des Sc., some very curious remarks upon an organ peculiar to these animals, which forms a sort of reservoir capable of containing a certain quantity of water, and placed immecliately above the branchicc. This accounts for the unusual convexity of the anterior sides of their thorax. |