scott: toxodonta of THE SANTA CRUZ beds. 
185 
No. 
No. 
No. 
No. 
No. 
No. 
15492. 
15,000. 15,336. 
15,969. 
15,256. 
15,487- 
Lower cheek-teeth series, length . 
. .180 
.200 
.198 
.203 
“ premolar series, length 
. .069 
.086 
•0795 
.074 
Pt» length 
• -oi35 
.017 
•0155 
.013 
“ width 
. .009 
.0105 
.011 
.0095 
Pj, length 
• -015 
.017 
.020 
.019 
.017 
“ width ..... 
. .013 
.013 
.013 
.015 
.014 
length 
. .018 
.021 
.023 
.0215 
.022 
.017 
“ width ..... 
. .015 
.0145 
.0125 
.016 
.016 
.014 
Py, length 
. .021 
.025 
.025 
.026 
.023 
.019 
“ width ..... 
. .016 
.017 
.014 
.018 
.018 
•oi55 
Lower molar series, length . 
. .110 
.127 
.112 
.120 
.129 
My, length 
. .027 
.031 
.031 
.029 
.029 
“ width ..... 
. .015 
.0165 
.015 
.0185 
.018 
M^, length 
• -034 
.038 
•034 
.036 
•0385 
.032 
“ width ..... 
. .0165 
.017 
.015 
.016 
.0195 
.020 
M^, length 
. .052 
.060 
.049 
•055 
.066 
•073 
“ width 
. .0175 
.017 
.014 
.015 
.020 
.016 
In the foregoing table No. 15,252 is the skull of a young animal, with 
dp— still in place. No. 15,135 is much the smallest adult skull in the 
collection, so that I was inclined to refer it to N. conspurcatus, but it is 
rather too large to be referable to that species ; it is a little older than 
the preceding individual and p- was already erupted, but not yet in use, as 
the crown is still much shorter than that of p- or m-. Though the total 
length of the upper dentition is so much less than in No. 15,252, it will 
be observed that the difference is chiefly in the anterior region and that 
the grinding teeth are of nearly the same size in the two skulls. No. 
15,000 is a fully adult skull, but still in early maturity, and Nos. 15,969 
and 15,256, which are of almost the same size, are beginning to show signs 
of age, while No. 15,487 is the mandible of a very old animal. The 
table brings out clearly the changes in the relative dimensions of the 
teeth, and especially of the last molar, which accompany increasing age. 
In the next table are given the measurements of the milk-teeth, taken 
from two individuals differing considerably in age and size. 
Measurements. 
Upper milk-dentition, length 
Di-, length (i. e. ant. -post, diameter) . 
“ width (i. e. transverse diameter) . 
No. 15,001. 
-?-i33 
. .010 
. .011 
No. 16,010, 
