936 OLDFIELD THOMAS 
breadth outside m! 8, inside m' 3.9; diastema 10; length of 
anterior palatine foramina 6.7; length of upper molar se- 
ries 7.0. 
Similar and allied to Mus jerdoni, but distinguished from that 
as from every other species of the genus by the hallux being 
opposable and provided with a small flat nail instead of a 
claw. | 
Size and proportions as in Mus jerdont. Fur long and straight, 
not really spinous in the single individual obtained but with 
a few flattened semispinous bristles intermixed with it, showing 
that in all probability the species is sometimes (either at a 
greater age or different season) spinous as in M. jerdoni. Ge- 
neral colour above rufous grey, the sides from nose to anus and 
the outer sides of the limbs and the upper surfaces of the hands 
and feet bright rufous. Belly sharply defined pure white, the 
hairs however sometimes tipped with rufous. Ears large, rounded, 
very finely covered with minute rufous hairs. Palate ridges 3 
pre- and 5 interdental. Hands with the claws on the digits II 
to V very small, slender and delicate; pollex with a broad flat 
nail as usual; hind-toes with large sharp claws, except that 
the hallux is provided with a nail, but a much smaller one 
than that of the pollex, not covering more than one third of 
its upper surface; this hallux is opposable to about the same 
extent as in Chiropodomys. Fifth fore toe reaching to the middle 
of the first phalanx of the fourth; fifth hind toe reaching to 
the middle of the second phalanx of the same digit behind. 
Palms and soles naked, pads large and rounded. Tail very long, 
evenly covered with short fine hairs, not pencilled; rings of 
scales averaging about 14 to the centimetre; its upper surface 
grey and its lower similar but slightly paler. 
Skull with a large rounded brain-case; supraorbital ledges 
well marked; anterior edge of wall of infraorbital foramen 
projecting very slightly forwards; posterior end of palatine fo- 
ramina barely reaching to the level of the front of m!. 
Teeth of ordinary size, their structure quite as in Mus, not 
as in Chiropodomys. 
