Harbour porpoise Although conjoined twins are rarely seen in wild mammals, the first known case of a two-headed harbour porpoise was documented in May 2017 when Dutch fishermen in the North Sea caught them by chance. A study published by the online journal of the Natural History Museum Rotterdam points out that conjoined twins in whales and dolphins are extremely rare. The harbour porpoise species is widespread in cooler coastal waters of the North Atlantic, North Pacific and the Black Sea. The populations in these regions are not continuous and are classified as separate subspecies with "P. p. phocoena" in the North
Tarzan and the Tarzan Twins it features Tarzan's first meeting with Doctor Karl von Harben, with whom he is already acquainted in "Empire". Because "Twins" is a children's book, however, it is customarily omitted from listings of the main Tarzan series. Thus "Tarzan, Lord of the Jungle" is generally considered the eleventh Tarzan book rather than "Twins". Two schoolboys, Dick and Doc, are cousins who resemble each other because their mothers are twins. As Dick is also related to Tarzan through his father, they become known as the Tarzan Twins. Invited to visit Tarzan's African estate, they become lost in the jungle and are imprisoned