Wallaroo and Wallaby

A Wallaroo is any of three closely related species of moderately large macropod, intermediate in size between the Kangaroos and the Wallabies. The name "wallaroo" is a portmanteau of wallaby and kangaroo. The term is not generally used by Australians. In general, a large, slim-bodied macropod of the open plains is called a "kangaroo"; a small to medium-sized one, particularly if it is relatively thick-set, is a "wallaby": most wallaroos are only a little smaller than a kangaroo, fairly thickset, and are found in open country. All share a particular habit of stance: wrists raised, elbows tucked close into the body, and shoulders thrown back, and all have a large, black-skinned rhinarium.

http://en.wikipedia.org/wiki/Wallaroo