io6 MAMMALIA—ORDER V.—RODENTIA. 



to having a species of Mus, Australasia is the home of four peculiar genera of 

 the sub-family. Of these, the mosaic-tailed mice ( Uromys), ranging from the 

 Aru Islands to Queensland, may be distinguished from Mus by the scales on 

 the tail being united by their edges so as to form a mosaic-like pavement, 

 instead of overlapping. The prehensile-tailed mouse (Chiruromys), of which 

 there is but a single species inhabiting the mountains of New Guinea, is 

 characterised by the naked tip of the tail being endowed with prehensile 

 power ; the scales of the rest of the tail being arranged in diagonal rows. 

 The upper molars have their tubercles very numerous, and arranged in a 

 complex manner ; while there are several peculiarities connected with the 

 structure of the skull. The numerous Australian species of jerboa-rats 

 {Gonilnrus) are easily recognised by their elongated hind-limbs, and long ears 

 and tail. They are inhabitants of desert districts, where they hop after the 

 manner of jerboas. The fifth genus (Mastacomys) is known only by a single 

 Tasmanian species, and differs from Mus by the great width of the molars, 

 and the reduction of the number of teats to four ; the fur being noticeable 

 for its length and softness. Differing remarkably as regards the latter feature, 

 the spiny-mice (Acomys), of which there are about seven small-sized species, 

 take their name from the fur being almost entirely replaced by flattened 

 spines. The skull and dentition are very similar to those of the type genus, but 

 the ascending process of each branch of the lower jaw is much smaller. 

 These mice range from Syria through East Africa as far south as Mosambique, 

 generally frequenting deserts, where some, at least, feed on bulbs. The long- 

 nosed rat (Echinothrix) of Celebes takes its name from the elongation of the 

 face, and is further characterised by the faint grooving of the incisors, and 

 the thick admixture of spines among the fur. Tlie small blind-mouse (Typh- 

 lomys) of China is sufficiently characterised by the minute size of the eyes, 

 which are almost concealed by the long lashes. Except that it has smaller 

 ears, it is otherwise very similar in appearance to a house-mouse. The 

 African pouched rats (Gricetnmys and Saccostomus) differ from all the other 

 members of the sub-family in being provided with cheek pouches, the single 

 West African species of the former having grooved upper incisors, whde in 

 the two representatives of the latter these teeth are plain. The last member 

 of the family is a mouse from Sumatra and Java, described as Fithechims, and 

 presenting a considerable external resemblance to Chirupodoniys. 



The mole-rats constitute a small family confined to the Old World and 

 characterised by their generally mole-like build, cylindrical bodies, short 



limbs, furnished with large claws, small or rudimental eyes 



The Mole-Eats, and ears, usually short or rudimentary tail, large incisors, 



— Family and rooted molars with re-entering enamel-folds on their 



Spalacidce. orowns. Premolars, varying in number, are present in 



some forms but wanting in others ; the palate is narrow; 

 and the anterior part of the zygomatic arch of the skull lacks the descending 

 vertical plate so characteristic of the Mnridm. The great mole-rat (Spaiaa; 

 typlilus) of South-Eastern Europe, South-Western Asia, and North-Eastern 

 Africa, which is the sole member of its genus, is the type of a sub-family 

 characterised by the angular portion of the .lower jaw arising from the lower 

 part of the sheath of the incisor in the manner characteristic of the 

 Myomorpha generally ; and also by the absence of premolars. It is a sub- 

 terranean animal, driving tunnels in the earth in search of the bulbs which 

 form its food, and has the eyes completely covered by skin, and rudimental 

 ears and tail. In the nearly allied bamboo-rats {Rhi~omys), of which there 



