792 RODENTIA 



Old World from Ireland to Japan, south to northern 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 m 1 ), 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 Palsearctic Muridse 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 OP APODEMUS. 



First lamina of m l with erescentic form raueh dis- 

 torted ; m 2 with no antero-external tubercle ; 

 interorbital region with conspicuously beaded 

 edges; back with blaeK median line (Eastern 



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



First lamina of m' with crescentic form not dis- 

 torted ; m? with small but distinct antero- 

 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 1 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 bufiy grey (Balkan Peninsula)... A. epinielas, p. 794. 

 First upper molar with three tubercles on outer 

 margin of crown ; alveolar width of m 1 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 largo, 

 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. fiavicoUis, p. 829. 



Underparts usually greyish white, the pectoral 

 spot usually forming complete collar and 

 spreading backward over chest (England) A./, mntonl, p. 831. 



