as Enemies of Mankind. 



39 



local races, sufficiently different from their parent race to be 

 regarded by many naturalists as distinct species. Over much of 

 continental Europe, particularly in the warm Mediterranean 

 region, a somewhat smaller form is found living a perfectly wild 

 life far from houses ; this outdoor mouse is called M. spicilegus, 

 and Miller and others regard it as perfectly indigenous. 



At various times remains of the House Mouse have been 

 recorded as fossils from British Pleistocene deposits, but the 

 writer, well acquainted with this branch of the subject, thinks 

 that no satisfactory evidence of the presence of this species in 

 Pleistocene Europe has as yet been found. In his view, the 

 House Mouse probably came to Europe from Asia with a people 

 not older than the Neolithic, and then spread all over Europe, 

 including the islands. While it continued to infest the habitations 

 of man in all places, individuals found that they could in certain 

 localities live quite well out of doors ; these, therefore, resumed a 

 wild habitat, and their descendants have developed into the peculiar 

 local or wild races mentioned above. All mice are plastic animals, 

 and the House Mouse is no exception to the rule. To-day, in 

 America, where no Murinae are naturally present, the House 

 Mouse is living in the fields as well as in the houses, and it is 

 developing local races or sub-species ; indeed, in South America 

 it is tending to lose its posterior molars, and if those teeth were 

 constantly absent, and we were ignorant of its history, the South 

 American animal would be classed by many zoologists as belonging 

 to another genus. 



General Habits. — The general habits of the House Mouse 

 resemble those of the Black Eat. It is a good climber and jumper ; 

 it swims well, but rarely takes to water voluntarily. Its senses, 

 with the possible exception of sight, are acute. Like rats, it shows 

 a propensity for following a beaten track, and of this advantage 

 can be taken when trapping is being done. Its nest of soft 

 materials is placed in any convenient recess — in walls, behind 

 skirtings, under floors or steps, in bookcases or other articles of 

 furniture, and in many other places. 



Its food comprises every description of human food, and even 

 tobacco; grain of all sorts and seeds of many descriptions are 

 readily eaten. 



Breeding" Habits. — House Mice are very prolific ; they 

 attain sexual maturity when three months old. The sexual season 



D 



