APODEMUS 503 



and unwieldy genus Mus is a constant object of systematists. 

 Most recent arrangements seem to have originated with 

 Hensel, who in 1856 {Zeitschr. deutsch. geol. Gesellsck, viii., 

 289) formed two groups, one containing norvegicus, rattus, and 

 musculus, the other sylvaticus, agrarius, and minutus. Hensel's 

 work, although much neglected or overlooked, was supported 

 by Forsyth Major in 1884 [Atti Soc. Tosc. Proc. Verb., iv., 

 129) and Thomas in 1905, the latter using Micromys to include 

 sylvaticus, speciosus, minutus, mystacinus, agrarius, harti, and 

 geisha. In 1908 Thomas substituted the earlier Apodemus for 

 Micromys, and in 191 2 Miller restricted the name to agrarius, 

 sylvaticus, epimelas, and their allies, the genus Micromys being 

 restricted to the Harvest Mouse {Mus minutus of Pallas) and 

 its allies. 



Characters : — The mice of this genus are rather generalised, 

 and not markedly modified by specialisation in any particular 

 direction. Their ears have no special meatal valves : their 

 tail is not prehensile. They have six or eight mammae, of 

 which two pairs are inguinal, and one or two pairs pectoral. 

 Their skull has the rostrum well developed, so that, unlike 

 that of Micromys, the diastema is distinctly longer than the 

 cranial depth at the anterior root of m^ ; the palatal shelf is 

 squarely or roundly notched behind by the posterior nares, 

 though sometimes provided with a short central spinous 

 process ; n^ and m^ are complex, having three cusps on their 

 inner sides (PI. XXVIII., Figs. 4-6, y, 6, 7). 



The genus is widely distributed in arctic, boreal, and 

 transitional regions of the Old World, from Ireland to Japan, 

 and from northern Skandinavia and corresponding latitudes 

 to the Barbary States of North Africa, Palestine, Persia, and 

 northern India. It is absent from Kamtschatka. It is first 

 known from the late Pliocene (Forest Bed) of England, and is 

 evidently of Old World origin. 



The complexity of the cheek-teeth is a primitive character 

 which assigns to Apodemus the lowest status among European 

 Murines. The combination of such cheek-teeth, non-prehen- 

 sile tail, and normal skull is quite distinctive amongst Paleearctic 

 genera, and is not exhibited by any Oriental or Australian 

 species. Some African mice (Thamnomys, Thomas, Ann. and 



