The front gallery, entered from the central hall, is devoted to Elephants and Sea-Cows, both living and extinct, and to extinct and fossil Mammals of other groups. Down the middle are placed a number of large and striking objects, of too great size to be contained in the wall-cases. The first is a nearly complete skeleton of the American Mastodon (fig. 41), an animal closely allied to modern Elephants, from which it is chiefly distinguished by the characters of its cheek-teeth. This is followed by a skeleton of the existing Indian Elephant (_Elephas maximus_), and the mounted skin of a tuskless male of the same species, brought home from India by His Majesty King Edward VII., when Prince of Wales. Further down the gallery is the skull of the extinct _E. ganesa_--remarkable for the immense length of its tusks--from the Siwalik Hills of India; and another of the Mammoth (_E. primigenius_), with huge curved tusks, in a perfect state of preservation, found in the Brick-earth at Ilford, Essex.[20] Then follow skeletons of the great extinct Irish Deer (_Cervus giganteus_), male and female, the former distinguished by its magnificent spreading antlers, resembling those of a Fallow Deer on a large scale. [Illustration: FIG. 41.--SKELETON OF THE AMERICAN MASTODON (_Mastodon americanus_). Greatly reduced.] The next central case is occupied by the skulls and portions of jaws of a remarkable horned hoofed quadruped, _Arsinoïtherium_ (fig. 42), from the Upper Eocene of the Fayum, Egypt. It belongs to an ancient group not closely related to any living animal. [Illustration: FIG. 42.--SKULL of _Arsinoïtherium zitteli_, from the Upper Eocene Strata of the Fayum, Egypt. About 1/12th natural size.] Equally peculiar is the _Toxodon_ (fig. 43) from the Pampas of S. America, of which a model of an entire skeleton is exhibited. [Illustration: FIG. 43.--SKELETON OF THE TOXODON (_Toxodon platensis_). From the Pampas Formation of Argentina. About 1/18th natural size.] Near by is placed a model of a skeleton of the _Dinoceras_ (fig. 44), one of the most remarkable of the many wonderful forms of animal life discovered in the Tertiary beds of the western portion of the United States of America. This animal combines in some respects the characters of a Rhinoceros with those of an Elephant, and has others altogether special to itself. The group to which it belonged became extinct in the Oligocene, or Middle Tertiary, period, without leaving any successors. [Illustration: FIG. 44.--SKELETON OF DINOCERAS. From the Eocene of Wyoming, U.S.A. One-thirtieth natural size.] [Sidenote: Sea-Cows.]