792 



RODENTIA 



01(1 World from Ireland to Japan, south to nortlicrn India and 

 the Mediterranean region of Africa. 



Characters. — Skull without special modifications of form, the 

 rostral portion well developed (diastema noticeably exceeding 

 depth of skull at anterior root of w}), the mesopterygoid fossa 

 squarish or broadly double- or single-rounded anteriorly ; first 

 and second upper molars with three cusps on inner side ; ear 

 without valve for closing meatus ; tail not prehensile ; fur 

 without spines. 



Remarks. — Among PahTearctic Miiridse the genus Apodemus is 

 well characterized by the complicated pattern of enamel folding, 

 the non-prehensile tail, and the normal skull. A similar combi- 

 nation of peculiarities occurs, however, in the African Thamnomys. 

 About a dozen species are known, seven of which occur in 

 Europe. 



KEY TO THE EUROPEAN FORMS OF APODEMUS. 



First lamina of m^ with crescentic form much dis- 

 torted ; m- with no antero-extenial tubercle ; 

 iuterorbital region with conspicuously beaded 

 edges ; back with blacli median line (Eastern 



Europe, west to Denmark) A. agrarius, p. 834. 



First lamina of to' with crescentic form not dis- 

 torted ; m^ with small but distinct autero- 

 external tubercle ; interorbital region with 

 edges not beaded ; back with no black median 

 line. 

 First upper molar with four tubercles on outer 

 margin of crown ; alveolar width of m^ equal 

 to about half greatest width of palate between 

 tooth-rows ; size maximum for the European 

 members of the genus, the condylobasal length 

 of skull not infrequently more than 30 mm. ; 



colour above huffy grey (Balkan Peninsula)... A. cpimelas, p. 794. 



First upper molar with three tubercles on outer 



margin of crown ; alveolar width of »i' less 



than half greatest width of palate between 



tooth-rows ; size never attaining maximum 



for European members of the genus, the 



condylobasal length of skull seldom attaining 



28 mm. 



Skull becoming massive and relatively angular 



in old age, the brain-case eventually with 



low but evident lateral ridges ; size large, 



the hind foot most frequently 25 mm. in 



length (23-27 mm.) ; condylobasal length 



of skull in individuals with noticeably worn 



teeth most frequently 26 mm. (25-29 mm.) A. flavicollis, p. 828. 

 Underparts usually creamy white, the pectoral 

 spot usually not forming complete collar 

 and not spreading backward over chest 

 (Continental Europe north of Mediter- 

 ranean region) A. f. flavicollis, -p. 829. 



Uiiderparts usually greyish white, the pectoral 

 spot usually forming complete collar and 

 spreading backward over chest (England) A.f. wintoni, p. 831. 



