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. 
„ breadth 
10*3 
10-6 
Brain case, breadth 
17-2 
17*3 
Anterior zygoma root 
5 3 
?» 
5*5 
Diastema 
10-4 
) ) 
10-7 
Palate, length 
21-9 
>> 
21*7 
Anterior palatina foramina . . . 
7-2 
71 
Upper molars, length 
8-1 
8*3 
Lower „ 
7-6 
>J 
8*0 
Condyle to incisor tip 
28-2 
5) 
28-2 
Coronoid tip to angle 
12-2 
JJ 
11*4 
are 
(M. 
twenty-five in number ; 
rattus , fide Thomas), 
in the longer 
the vertebras 
The caudal vertebrae 
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 
