HORN EXPEDITION—MAMMALIA. 
47 
It was only after examining twenty-nine specimens that one was found in 
which the full number of incisors was present in the upper jaw, whilst in only a 
comparatively few specimens an additional premolar was present in the lower jaw, 
always small and pushed out to the side of the jaw, in front of the first molar. 
4 12 
The full dentition so far as at present known is i. — c. p,m. -. 
3 1 3 
m. 
4 
4’ 
In the specimens in which it is present the upper is implanted 
immediately in front of the premaxillary suture, and the presence of this tooth 
serves to eliminate one of the features in which, as recorded by Dr. Gadow (and 
so far as the material available up to that time existed), Notoryctes might be 
regarded as differing from recent marsupials. 
Dr. Gadow remarks that “the most remarkable feature is, however, that the 
reduction either in numbers above or in size, or in both, is undoubtedly greater in 
the left mandible than in the right. This fact seems well estnblished, considering 
that out of the nine specimens examined the left-sided reduction is greater in not 
less than eight specimens; reduction in size alone in three, in numbers in five 
specimens. The total number of teeth in the nine right mandibles is eighty-six, 
in the corresponding left mandibles only seventy-nine. The number of reduced 
and of absent teeth on the right side is eleven, on the left side nineteen. Such a 
decided asymmetry is practically unique. I have failed to perceive any corres¬ 
ponding asymmetry in the size of the two mandibles.” 
I have carefully examined the teeth of a large number of specimens, and give 
the rough results, so far as numbers are concerned, which are derived fi'om twenty- 
five of them :— 
Left Upper Jaw. 
Three specimens with 8 teeth each ... ... 24 
Six specimens with 9 teeth each ... .... 54 
Fifteen specimens with 10 teeth each ... 150 
One specimen with 11 teeth ... ... 11 
Total ... ... ... 239 
Right Upper Jaw. 
One specicemen with 7 teeth ... ... 7 
One specimen with 8 teeth ... ... 8 
Eight specimens with 9 teeth each ... ... 72 
Fifteen specimens with 10 teeth each ... 150 
Total ... ... ... 237 
