Page:Mammalia (Beddard).djvu/149

 is one strong pair, with occasionally one or two rudimentary incisors. The upper canines, if present, are not large. The molars are tuberculate or ridged. All Marsupials (except the Wombats) to some extent, and the Macropods especially, are characterised by the prolongation of the tubes of the dentine into the clear enamel. The significance of this fact is, however, lessened by the fact that the same penetration of the enamel by dentinal tubes occurs in the Jerboa, the Hyrax, and some Shrews. The feet have two syndactylous toes, less marked in the Wombats than in the Kangaroos and Phalangers.



This order is mainly Australian at the present day, using the term of course in the "regional" sense (see p. 84); the only exception indeed to this statement is the occurrence of the genus Caenolestes in South America. But it is now known that Diprotodont Marsupials formerly existed in the same part of the world.



'''Fam. 1. Macropodidae.'''—This family contains the Kangaroos, Wallabies, Rat-Kangaroos, and Tree-Kangaroos. With the exception of Dendrolagus