THE HARVEST MOUSE 563 
the Harvest Mouse is characterised by the great development of the 
cerebral, and the corresponding shortening of the facial regions. 
The smooth, ovate, evenly inflated brain-case nearly equals, and in 
Far Eastern sub-species occasionally exceeds, the zygomatic breadth in 
width. The parietal region is well vaulted; the edges of the short 
inter-orbital region are quite sharp, though not ridged. The anterior 
edge of the masseteric plate is straight, not curving forwards, and it 
scarcely projects beyond the front edge of the slender roof of the 
infra-orbital canal. The nasals fuse with each other at an early stage 
of growth; they are short and rather narrow; the processes of the 
premaxillz supporting them in front are but weakly developed. The 
diastemata are short, the anterior palatal foramina are relatively about 
as in A. flavicollis, Notwithstanding the shortness of the rostrum, the 
palatal length is about as great relatively as in A. sy/vaticus; this 
is due to the greater development of the posterior palatal shelf, which 
in this genus has a structure very similar to that of M/ccrotus (cf. Fig. 89 

Fic. 89.—SKULLS OF Afpodemus and Micromys. 
Apodemus sylvaticus, (1) dorsal, (2) ventral view ; A/icromys minutus, (3) dorsal, 
(4) ventral view. (1-4 life size.) (5) Palate of A/icromys (3 times life size). 
with Fig 73D. above, p. 459). Posterior lateral bridges and fosse, and 
a posterior median septum, the ventral surface of which is frequently 
slightly grooved, can all be distinguished just as in JJvcrotus, but 
these parts, in correlation with the brachyodont teeth, are, of course, 
sculptured in lower relief in M/zcromys, and they are situated behind, 
instead of between, the tooth-rows. The inter-pterygoid space begins 
about 1 mm. behind the tooth-rows, and is narrower in front than 
behind. The basi-occipital is compressed slightly, its anterior width 
being less than its median length, and the median ridge and lateral 
furrows of its ventral surface are well defined. The bulle are of 
large size and rounded form. The following proportional measure- 
ments (condylo-basal length=100), obtained from a series of skulls 
representing nearly all known sub-species of M7. minutus, may be 
compared instructively with those of Apodemus given in the tables 
at pp. 519 and 539 above :—(5) Cranial width, 51-7 to 57-8; (6) cranial 
depth, 30-9 to 36-6 ; (7) post-molar length, 48 to 50-9; (8) condyle to 
