28 



Bulletin American Museum of Natural History 



[Vol. XL VII 



The results of the foregoing analysis of variation in size as affected 

 by age and sex are collated in the following tabular resume (Table 5) . 



The results derivable from the above tabulation would possess 

 greater interest if the number of specimens in each of the six categories 

 had comprised a more nearly equal number of specimens — if each had 

 been as large as in Table 3. It seems safe to assume (1) that size is not 

 diagnostic of sex ? although the above statistics indicate a slight superiority 



Table 5. — Relation of Age and Sex to Size 



Condition of Teeth 



No. of 

 Specimens 



Total 

 Length 

 Animal 



Condylo- 



incisive 



Length. 



Skull 



1. 



Entire milk set only 



6 



451 



56.3 



2. 



m* 



Entire milk set plus — more or less developed 



5 



501 



60 5 







[38 



514 



62.3 



3. 



Permanent set, unworn 



{24 a' 



509 



62.1 







[l4 9 



524 



62.8 







f8 



516 



62.3 



4. 



Permanent set, slightly worn 



i QJ 



520 



62.5 







{ 29 



501 



61.5 ' 







f 9 



524.4 



63.27 



5. 



Permanent set, much worn 



\ 4 c? 



523 • 



63.25 







1 5 9 



527 



63.5 







fH 



512 



62.9 



6. 



Permanent set, greatly worn 



{ 7 <? 



511 



62.6 







{ 4 9 



514 



63.5 



for the females. The largest specimen of the entire series is a "young 

 adult'' male (No. 49445), with a total length of 556 mm., a tail length of 

 265, length of hind foot 89, and condyloincisive length 63.5, dimensions 

 not reached by any female, except the skull length in a few old females, 

 which again is exceeded by a few old males. (2) There is a slight increase 

 in size, both externally and of the skull, in the old-age period, but insuffi- 

 cient to antagonize the selection of young adult specimens as types of new 

 forms, since individualism in any age class more than bridges the differ- 

 ences that can properly be ascribed to age after approximate maturity 

 is reached. 



