Pennant states that this species inhabits rocky coasts, and is the most delicious meat of any, and that it mats its shell between Christmas and Easter. " There are some species," says Edwards., in his article Crustacea,' in the Cyclomedie of Anatomy and Physiology,' "such as the crabs and the Brachyura generally, in which the carapace presents a considerable expansion on either side, forming two large compartments in which the greater mass of the thoracic viscera is contained. Under these circumstances it would be impossible for the animal to escape from its dorsal covering by the relatively inconsiderable opening which this part presents on its inferior aspect. This renders it necessary that the carapace, instead of being cast off by simply rising in a single piece, should give way and separate in some direction or another, and this it does by splitting along the curved lines, extending on either side from the mouth to the origin of the abdomen, in the course of which the epimeral pieces cohere with the dorsal one." (Collinson, 'Phil. Trans.' 1746 and 1751; 'Hist. Nat. des Crustacas; t. 1, p. 56.) Sir Charles Lyell says (` Principles of Geology' ), " A large female crab (Cancer Pagurus) covered with oysters, and bearing also Anomie Ephippium and Act in ice, was taken in April, 1832, off the English coast. The oysters include individuals of six years' growth, and the two largest are four inches long and three inches and a half broad. Both the crab and the oysters were seen alive by Mr. Robert Brown. This specimen is in the collection of my friend Mr. Broderip, who observes that this crab, which was apparently in perfect health, could not have cast her shell for six years, whereas some naturalists have stated that the species moults annually, without limiting the moulting period to the early stages of growth of the animal."
The genus Cancer of Linnmus included a large number of species, and the term Crab, which is a translation of it, is in common parlance applied to the great bulk of the Brachyurous Crustaceans.
For the Blood-Spotted Crab of the Asiatic seas (Cancer maculatus, Linn., &c.) and the Coralline Crab (Cancer cora2linus, Fabr.), Dr. Leach instituted the genus Carpilius, characterised by the existence of a single tooth on the border of the carapace, and by the tridentated front; and, for the Eleven-Toothed Crab (Cancer unclecimdentatus, Fabr.), the carapace of which is smooth, with 11 crenulated teeth on each antero-lateral border, and black toothed fingers, spoon-shaped at the end, he founded the genus Clorodius or Chlorodius. Milne-Edwards enumerates four species of Carpilius and seven of Chlorodius. He considers the fossil Crabe aux Grosses Pinces, Cancer macrochelus, Desm. (' Hist. Nat. des Crustac*s Fossiles,' p. 91, pL vii. fig. 1-2), Cancer Lapidescens, Rumph. (`Amb. Rariteit Kamer,' pL 60, f. 3), as referrible to the genus Carpilius rather than to the division of Crabs properly so called. It should be remembered that Milne-Edwards's genus Cancer (Crabs) differs from that of Leach. The former includes under that name such forms as Cancer roseus (Carpilius roseus of Riippell), C. lobatus, C. esculptus, C. limbatus (Xantho granutosus, Riip.), C. Sarignii and C. Acanthus, excluding Leach's Cancer, the type of which is the eatable Crab of our coasts, to which form Milne Edwards gives the name Platycarcinua. It does not appear that any species of Cancer, Leach, Plat yea rc inns, Milne-Edwards, has been found in a fossil state.