192 
RECORDS OF THE AUSTRALIAN MUSEUM. 
Teeth. — The front edges of the upper incisors are of particularly 
deep orange colour, the lower ones are somewhat paler. The molars 
are relatively and actually larger than those of Mus decumanus , 
and are noticeably broader ; the upper series converge anteriorly, 
and are somewhat bowed outwards. 
Fig. 2. 
Fig. 3. 
Fig. 4. 
Dimensions of Skull. 
A. 
B. 
$ 
Greatest length 
40*3 mm. 
39*6 
mm. 
Basal length 
36-6 „ 
36-2 
9 9 
Greatest breadth 
21-9 „ 
21-7 
Nasals, length 
150 „ 
14-4 
9 9 
5 j 
,, greatest breadth 
4-6 „ 
4 6 
Interorbital breadth 
53 „ 
5‘6 
• i 
Interparietal length 
4*1 „ 
4-6 
j > 
9 9 
„ breadth 
10-3 „ 
106 
Brain case, breadth 
17-2 „ 
17-3 
3 J 
Anterior zygoma root 
5 3 „ 
5*5 
' s 
Diastema.,. 
10-4 „ 
10-7 
/ / 
9 5 
Palate, length 
21-9 „ 
21*7 
9 9 
Anterior palatina foramina . . . 
7-2 „ 
71 
9 9 
Dpper molars, length 
8-1 „ 
8-3 
9J 
Low er „ 
7-6 „ 
8’0 
99 
Condyle to incisor tip 
28-2 „ 
28-2 
99 
Coronoid tip to angle 
12-2 „ 
11*4 
*9 
are 
(M. 
twenty-five in number ; 
rattus, fide Thomas), 
in the longer 
the vertebrae 
The caudal vertebrse 
tailed Mus arboricola 
number thirty -eight. 
Waterhouse described the colour of the lower incisors as black, 
evidently a peculiarity of the individual examined. Gray, writing 
on Mus lutreola remarks, “front teeth yellow”; while Gould 
says, “the incisor teeth are orange-coloured.” I do not remember 
having examined a rat’s skull in which the incisor teeth are so 
deeply tinted. The writers quoted describe the under parts of 
