8 MURES CELEBENSES. 



ible spines: on the back they are slate-coloured near the 

 base, rusty towards the tip, on the belly they are enti- 

 rely white ; the woolly hairs being here slate-coloured near 

 the base and for the rest of a pure white. 



A simular phenomenon may be observed in the African 

 Squirrels , among which occur the only species with harsh 

 spines. Every one who has been engaged in the study 

 of these species must confess that it is exceedingly dif- 

 ficult to distinguish them accurately , because the descri- 

 bers of new species hardly ever pay attention to the 

 nature of the fur. Without having seen the types it is 

 next to impossible to determine the species with exact- 

 ness. 



My reason for not giving a generic name, for instance 

 Acanthomys or Acomijs, to the species of Mice with spi- 

 nous hairs , is that , in doing so , I should make an ar- 

 tificial division , dislocating species which belong together 

 in a natural system. If moreover it would be advisable 

 to distinguish by a generic name the Mice with harsh and 

 strong spines, it would be equally necessary to combine 

 into a separate genus those species of Mice of which the 

 spinous hairs , although flattened and mostly channeled , 

 are so narrow and flexible as not to deserve the name of 

 » spines". 



With the African Squirrels the case is different. The sci- 

 uri with harsh spines are here separated under the name 

 »Xerus^\ and with good reason. They are Ground-Squir- 

 rels and differ in habits and habitation from the other 

 soft hairy African Squirrels. 



I. ^VITH SPINOUS HAIRS. 



1. 31 us leucopus. 

 Acanthomys leucopus, Gray, P. Z. S. L. 1867, p. 598. 

 n. i. toerean in pate. 



Upper parts grayish brown ; sides of nose , cheeks , chin , 



Notes from the Leyden Nueeuin. 



