CHAP. XVII.] 



MAMMALIA. 



229 



last Catalogue (1873) he divides the genus into three Hyrax, 

 JEuhyraXj and Dendrohyrax the latter consisting of two species 

 confined apparently to West and South Africa. 



No extinct forms of this family have yet been discovered ; the 

 Hyracotherium of the London clay (Lower Eocene) which was 

 supposed to resemble Hyrax, is now believed to be an ancestral 

 type of the Suidae or swine. 



Order X.EODENTIA. 

 FAMILY 55. MUKHXE. (f f Genera, 330%ecies.) 



GENERAL DISTRIBUTION. 



The Muridae, comprising the rats and mice with their allies, are 

 almost universally distributed over the globe (even not reckon- 

 ing the domestic species which have been introduced almost 

 everywhere by man), the exceptions being the ^thre& insular 

 groups belonging to the Australian region, from f $'M of which 

 have any species yet been obtained. Before enumerating the 

 genera it will be as well to say a few words on the peculiarities 

 of distribution they present. The true mice, forming the genus 

 Jfe*B distributed over the whole of the world except N. and S. 

 America where not a single indigenous species occurs, being 

 replaced by the genus Hesperomys ; five 7 other genera, compre- 

 hendin^all the remaining species found in South America are 

 peculiar to the Neotropical region. Tlfre^e genera are confined to 

 the Palsearctic region, and three others to the Nearctic. No less 

 than twelve genera are exclusively Ethiopian, while only three 

 are exclusively Oriental and tirSS Australian. 



Mus (100-120 sp.) the Eastern Hemisphere, but absent from the 

 Pacific and Austro-Malayan Islands, except Celebes and Papua ; 

 Lasiomys (I sp.) Guinea; Acanthomys (5-6 sp.) Africa, India,and 



