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TECTIBRANCHIATA.—APLYSIADÆ.

nomenon in a West Indian species, and Mr. Patterson thus speaks of it in our native species, A. hybrida. "The first which our dredge brought up was placed on one of the rowing benches of the boat, and in a very short time emitted a rich purplish fluid, so copiously, that it ran along the board. Being transferred to a phial of sea-water, the purple dye was still given off in such abundance that the creature soon became indiscernible. It was not until the water was again changed that we had the opportunity of observing the ease and grace with which it moved about, elevating and depressing its mantle, altering the outline of its body, and extending and retracting its tentacula so incessantly, that an artist would have found a difficulty in catching its characteristic figure." This fluid is said by Professor Goodsir to be secreted by the edge and internal surface. The secreting surface of the mantle consists of an arrangement of special nucleated cells, which are distended with a dark purple matter.

Besides the purple secretion, the Sea-hares occasionally discharge, from an orifice situated behind the oviduct, a milky fluid highly acrid, and probably containing stinging thread capsules similar to those already described in Eolis. The Seahares have in all ages sustained the imputation of being highly offensive and injurious to man, and though in modern works it has been the custom to ridicule the charge, there is reason to think it may not be altogether groundless. Barbut declares that a sailor, in the Mediterranean, happening to take hold of an Aplysia, it gave him such instantaneous and excruciating pain, as to cause inflammation and