Arsindithermm Zitteli. 531 



-subject of a monograph by the late Professor Marsh, of Yale. They 

 are as large as a large rhinoceros, and have as many as three 

 impairs of horns ; none, indeed, quite so big as the front pair of 

 Arsinoitherium, but often of respectable size. Many kinds are 

 known, and the complete skeleton has been put together. They 

 form a group known as the Amblypoda, and it is recogffised as 

 characteristic of this group that the feet and limb bones are similar 

 in character to those of elephants. The teeth are very different 

 from those of Arsindithermm. A full-sized model of a complete 

 skeleton of a Dinoceras is exhibited in the east gallery of the 

 Natural History Museum. It is probable that the Amblypoda and 

 • Arsimitlierium are representatives of a group of great mammals 

 which sprang from ancestors common to them and to the elephants — 

 before the peculiar tusks and the trunk of the elephant had been 

 developed. The hollow brain-case of Arsinoitherium has enabled us 

 to study the shape of its brain by means of casts, and this will throw 

 light on its affinities with elephants and Dinoceras. 



"The question naturally arises as to what was the special use to 

 Arsinoitherium of its two huge horns. The use of horns is in almost 

 all cases either for defence against animals of prey or for those fierce 

 contests between the males of a species in which the victor becomes 

 lord of a number of females. Possibly both purposes were served 

 by the horns of the Arsinoitherium,. 



" The skulls and bones oi Arsinoitherium, described by Mr.Beadnell, 

 belong to a single species to which he gave the name A. Zitteli, 

 after Professor Zittel, of Munich. The lower jaw of this species is 

 1 ft. 8 in. in length. To this species belongs the specimen figured 

 in the photograph, and it is a sufficiently huge and astonishing 

 ^monster. But Dr. Andrews has this year brought back from the 

 Fayum a lower jaw of an Arsinoitherium, which is one-third as large 

 again, namely, 2 feet in length (73'5 cm.). There is no doubt that 

 this is a distinct and larger kind of Arsinoitherium, much bigger 

 than the biggest existing rhinoceros. I name it Arsinoitherium 

 Andrewsii, in recognition of the remarkable ability, courage, and 

 perseverance shown by Dr. Andrews in the elucidation of the fossil 

 mammals of the Fayum." , 



It may not be inappropriate to mention that for the carrying out 

 of Dr. Andrews' last expedition to the Fayum, which resulted not 

 only in securing a valuable series of vertebrate fossils, but the 

 especially fine and complete head of Arsinoitherium Zitteli and the 

 jaw and portions of the cranium of Arsinoitherium Andrewsii, 

 the National Museum is indebted to the liberality of that 

 enthusiastic naturalist W. E. De Winton, Esq., F.Z.S., for some 

 time past the very able Acting Superintendent of the Zoological 

 Society's Gardens, Eegent's Park. 



EXPLANATION OF PLATES XXIII AND XXIV. 



Plate XXIII. — Profile of skull of Arsinoitherium Zitteli, Beadn., from tlie 

 Upper Eocene of the Fayum, Egypt. 



The dotted white line on this Plate indicates the extreme length of the mandible, 

 ■viz. 20 inches. 



