54 The Scottish Naturalist. 



Ultima T/iule, for the absence from Shetland of any land animal 

 (except the half-aquatic Otter) seems to indicate that those 

 islands were already separated before the arrival of any form of 

 mammalian life. 



" Such a hypothesis of the dispersal of English mammals 

 through Scotland and Ireland appears to me to be the only 

 one which explains the peculiarities of their present distribu- 

 tion, and is likewise in accord with the facts of physical geo- 

 graphy. Should it be accepted, the recent and extinct mam- 

 mals of Scotland may be arranged in five categories, in the 

 order of the dates of their immigration. This I have attempted 

 to show in the following list, in which the extinct species are 

 marked with an asterisk : — 



" List of Extinct and Recent Scottish Mammals arranged in 

 the probable order of their arrival from the southward. 



I. Before deposit of boulder clay — 



* Elephas primigenius. * Rangifer tarandus. 



II. Before separation of Ireland — 



Erinaceus europ&us. * Eqinis caballus. 



So rex minutus. % Sus scrofa. 



* Cants lupus. * Megaceros gigauteus. 

 Can is vulpes. Ccrvus elaphus. 

 Martes sylvestris. Sciurus vulgaris. 

 Mustela ermiuea. Mus sylvestris. 

 Meles taxus. Lepus variabilis. 

 Lutra vulgaris. Lepus cuniculus. 



III. Before separation of Hebrides — 



Sorex tetragoniwus (?). * Bos longifrons. 



A n 'icola a gr est is. 



IV. Before separation of the Orkneys : — 

 Crossopusfodie/is. Arv icola amphibius. 



* Bos pi'imigeiiius. 



V. Since separation of Orkneys — 



Talpa europcea. Capreolus caprcea. 



Felis catus. * Castor fiber. 



* Ursus arctos. Mus minutus. 

 Mustela vulgaris. Arv icola glareolus. 

 Mustela putorius. Lepus europceus." 



* A Ices machlis. 



The weak points of the above interesting hypothesis put 



