The Thrasher (Alopias Vulpes), also called slasher, sea-fox, fox-shark, and sea-ape, is a shark caught now and again on the Cornish and other parts of our coasts. Its peculiarity is an enormous tail-fin which is sometimes as long as its body. With this it is popularly supposed to thrash the water for such purposes as driving away dolphins, and herding together shoals of fish. In 1865 Mr. Blake-Knox is said to have seen one 'kill a diver with its tail and then swallow it.' (Which, the tail or the diver ?) Many observers have declared that the thrasher uses its enormous tail to flog whales to death, and though this remarkable peculiarity has been doubted, yet evidence in support of the statement is very strong. Very long thrashers have been caught off the coast of England, but their length is misleading, being made up of more than half tail. There is on record a Plymouth thrasher of fourteen feet, and one of a similar length was caught off Dawlish.