Bottlehead, or BOTTLENOSE (Hyperoodon), one of the toothed whales in the same family as the Sperm (Physeteridae). The most striking feature is the abrupt rise of the head from the small snout. The bones forming the front of the upper jaw rise suddenly behind the nostrils, expanding in crests as they ascend. The result is a rounded and prominent upper head. There is a small conical tooth hidden in the gum at the end of each lower jaw, and sometimes another behind this again. The blow-hole is crescent-shaped. The colour is blackish, verging to white below. Two species are certainly known, both from the North Atlantic, and sometimes found in the North Sea. H. rostratus (or bidens, or butzkopf), the common Bottlenose, measures about 24 feet in length, and is sometimes stranded on European shores. One described by Hunter in 1787 was caught above London Bridge. H. latifrons is somewhat larger, has a flatter forehead, and attains a length of 30 feet. The genus Xiphus is closely allied. The Hyperoodon must be distinguished from the Bottle-nosed Dolphin (Delphinus tursio) occasionally found on British coasts. See CETACEA, WHALE.