The moment chosen by the artist is when Dianora rushes from her house into the midst of the crowd, and reaches Hyppolito, surrounded by priests and soldiers. It is easy to see to what a varied expression of passion and action this point of the story gives rise. A CURIOSITY IN NATURAL HISTORY. The crustacean class of animals, of which the lobster, crab, and shrimp are familiar examples, have this peculiarity of structure--that their soft bodies are inclosed within a coat-of-mail formed of carbonate and phosphate of lime. In fact, they carry their skeleton outside their bodies, both for defense of the vital parts within, and for the attachment of the muscles which move their limbs, and every part of their frame. No warrior of old was ever more completely enveloped in his hard coat-of-mail, with its jointed greaves and overlapping scales, than is the lobster in its crustaceous covering; with this exception, that the warrior could at pleasure unbuckle himself from his armor, whereas the body and limbs of the crustacea are completely incased in hollow cylinders, firmly and accurately jointed, from which there is no such ready release. Now, as this shelly integument envelops them from their earliest youth, and as it does not expand and grow, the natural growth of the soft body beneath would be entirely prevented did not nature supply a remedy of a very curious kind--the exuviation, or periodical throwing off of the external crust, and the formation of a larger shell-covering fitted for the increasing growth of the animal. This is a circumstance which has long been familiar to naturalists, and indeed the most ordinary observer must have often remarked in the crabs and lobsters brought to table, appearances indicative of their change of external coverings. In the back of the edible crab, may often be noticed a red membrane lining the inner side of the shell, but so loose as to be readily detached. Along the greater part of its course this membrane has already assumed a half-crustaceous consistence, and is just the preparatory process to the old shell being thrown off by the animal. There is another curious circumstance which has also been long known--that crabs and lobsters can renew lost limbs. Some misconception, however, had existed regarding the manner in which this was effected, until the observations of the late Sir John Dalyell have thrown more accurate light upon the subject.