EXOACANTHA, in botany, a genus of the Pentandria Digynia class and order. Natural order of Umbellate. Essential character : involute spiny ; involucle halved, with unequal rays ; flowers alt hermaphrodite, with equal, inflex, heart shaped petals; seeds ovate, striate. There is but one species, viz. E. heterophylla, found by Billardiere near Nazarolt. EXOCCETUS, the flying fsh,in natural history, a genus of fishes of the order Abdominales. Generic character : head scaly ; mouth without teeth ; jaws con nected on each side ; gill membrane ten-rayed ; pectoral fins very long and large, and giving, to a certain degree, the power of flight. There are five species. Vtre shall particularly notice the E. exi lien, or the Mediterranean flying fish, This is about fourteen inches in length, and is found principally in the Mediter ranean and Atlantic Seas, frequently alone, and sometimes in small companies. By the extraordinary length of its pecto ral fins it is enabled to quit the water and support a flight, about three feet above the surface, for the distance of eighty or a hundred yards, after which it is obliged to return to the water and moisten its fins, which, even in this short progress, become hard and dry. These
fishes are persecuted by the dorado un der the water, and by the gull, or alba tross, above the surface of it, and thus of ten escape destruction by the one, only to incur it from the other. This faculty of maintaining short flights in the air is possessed by several other fishes, parti cularly by the scorpena and the trigla. The air-bladder of the flying fish is ex tremely large, and, of consequence, highly assisting to its aerial progress. The roe of this fish is reported to be highly caustic ; the smallest quantity ap plied to the tongue producing some de gree of excoriation. For a represents tion of the oceanic flying fish, see Pisces, Plate IV. fig. 2.