Fox Shark (Alopecias vulpes), the single species of the genus, occurring sometimes on the British coast, and common in the Atlantic, some parts of the Pacific, and in the Mediterranean. The maximum length is 15 feet, of which half is taken up by the caudal fin, which has the upper lobe enormously prolonged. The teeth are of moderate size, anal and second dorsal small, pectorals and first dorsals large. These fish prey upon herrings, pilchards, and sprats, and from their beating the water with their tail to frighten their prey, they are often called Threshers. There is no foundation for the story that they attack whales.