HORN EXPEDITION-MURIDS. 
407 
herein mentioned are too young to enable one to judge of the identity or otherwise 
of the species, but tlie peculiarity of the greatly broadened molars leaves little 
doubt as to the correctness of assigning them to the genus. There are differences, 
such as the colour of the ventral surface, the comparative length of the ears and 
tail and the form of the anterior zygoma root, which seem to be too wide to be 
accounted for by immaturity. The following description may therefore be useful 
when adult specimens are obtained. 
Habit, vole-like. Fur exceedingly long and thick; general color rich 
reddish-brown above, yellowish beneath. All the hairs grey at the base. Ears of 
medium size, greatly hidden in the fur, clothed with longish brown hairs; laid 
forward, they do not reach the eye by a diameter. Limbs and toes brown. Tail 
shorter than the head and body, dark brown above, yellow beneath; hairs long, 
hiding the scales, which average twenty-three to the centimetre. 
Skull rather stout; the anterior zygoma root does not project above, the 
angle being rounded and the front edge slightly concave. The anterior palatina 
foramina extend backwards to just within the front margin of ;/d. 
Teeth .—As far as can be ascertained, the teeth are as in Mastacomys fuscus, 
but the anterior molars appear to be slightly more separated. ;/d, all the cusps 
excepting the posterior one are worn so as to expose tlie enamel ridges, the 
anterior cusps only have had the summits removed, while has not emerged to 
the level permitting abrasion. 
Palate ridges .—Three predental undivided, five interdental interrupted. 
Dimensions. 
A. g 
B. $ 
C. 2 
D 2 
Head and body 
- 
64 5 
64'0 
63-0 
580 
Tail - - - - 
63 5 
61'8 
61 5 
50-8 
Length of head 
- 
24.-5 
24-4 
23-7 
23 8 
Muzzle to ear 
- 
17-4 
20-8 
17-0 
18T 
Ear ... - 
- 
7-9 
8-5 
91 
70 
Forearm and hand 
- 
19-0 
172 
20 0 
17'2 
Hind foot 
- 
17-0 
19-5 
18-5 
18-5 
Heel to front of last foot-pad 
- 
7-5 
9-0 
8-5 
8-4 
