224 
PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 
No. 15,131. No. 15,136. 
No. 15,003. 
Iy, width ..... 
.008 
.010 
.008 
h > length 
.008 
•0055 
.005 
“ width ..... 
.0105 
.013 
.010 
I ¥ , length 
.014 
.014 
.012 
“ width 
.010 
.010 
.007 
Lower canine, length 
.010 
.009 
.0085 
“ “ width . 
. .0045 
.004 
.0045 
“ cheek-teeth series, length . 
. .105 
.102 
.091 
“ premolar series, length 
• .043 
.044 
.038 
P T , length 
.008 
.007 
.0075 
“ width 
.005 
.0045 
.0043 
P^, length 
.009 
.010 
.010 
“ width 
.006 
.006 
•0055 
Py, length 
.Oil 
.012 
.010 
“ width 
.007 
.0075 
.007 
Py, length 
.0125 
•0135 
.0115 
“ width 
.008 
.007 
.0073 
Lower molar series, length 
.062 
•059 
•053 
My, length 
.014 
.016 
.0145 
“ width 
.008 
.008 
.007 
Mj, length ..... 
.0185 
.019 
.017 
My, length ..... 
. .030 
.025 
•0235 
“ width ..... 
.008 
.008 
.007 
Aside from the effects of age and wear, 
these measurements, 
it will be 
observed, agree quite closely. 
The effects of abrasion are clearly shown, 
for example, in the very small size of I 1 in No, 15,131, which is 
quite an 
old female and in which 
the median 
upper incisors are 
worn to 
mere stumps. In the old animals also 
the third molar is 
relatively 
larger, as appears from a comparison of the measurements of Nos. 15,131 
and 15,003, the latter a young and quite small female. The other indi- 
viduals are males and No. 
15,136 is 
especially large and 
robust ; 
the skull has the frontal protuberance, 
but the upper cheek-teeth are 
unfortunately all missing. 
Several young individuals 
enable me 
to give the dimensions of the 
milk-teeth, but the skulls in all cases but 
one have lost the lower jaw. 
Measurements. 
No. 15,159. No. 15,945. No. 16,011. 
No. 15,114. 
Upper milk-dentition, length 
.085 
.082 
•0835 
Di 1 , length (i. e. ant. -post, diameter) 
.004 
.004 
.0043 
“ width (i. e. transv. diameter) 
.Oil 
.Oil 
.013 
