as Enemies of Mankind. 



55 



foramina are very long, narrowing behind, and terminate 

 opposite the middles of the front molars (in all other British 

 species these foramina terminate in advance of the molars). 

 House Mouse, Ifws musculus. 



Fig. 3. — Upper Incisors of Battus {a) and Mus [h). 

 Much enlarged. 



Of the four genera of Murinae dealt with above, two, Apodcium 

 and Micromys, are indigenous to Britain ; the former, at all events, 

 was established in this country by the end of the Pliocene period. 

 As compared with the alien genera Battus and Mus, they appear 

 to be less highly developed in many ways ; in particular they have 

 retained a comparatively complex dentition. The Harvest Mouse, 

 nevertheless, is very highly specialized for its peculiar life among 

 the corn-stalks. This specialization is visible in the diminutive 

 size of the animal, and it is also betrayed in many of its organs, 

 e.g., in its foot-pads, which are modified for special use as 

 climbing irons." 



E 



