ANNALS OF SCOTTISH NATURAL HISTORY 



my request. I am also deeply indebted to him for the 

 drawings of the teeth. 



An examination of the skull of Microtus orcadensis 

 (Millais), and a comparison of it with the skulls of other 

 British species of Microtus and of Evotomys glareolus, the 

 Bank Vole, disclose many features from which it may be 

 contended that the Orkney Vole merits a place as a distinct 

 species among the British mammalia. Measurements of the 

 skull of this animal have been made according to a method 

 of craniometry suggested some short time ago. 1 These 

 measurements, and the indices computed from them, as well 

 as similar measurements and indices of other species of 

 Microtus and Evotomys, are given in the following table : 



From the above indices it is seen that the skull of 

 Microtus orcadensis agrees in no one point with the skulls of 

 all the other species. In some instances the difference is 

 not great, and it may possibly be argued that similar differ- 



1 'A Method of Craniometry for Mammals,' "Proc. Roy. Phys. Soc. of 

 Edinburgh," vol. xv. 1902. 



