10 
JOURNAL OF MAMMALOGY 
we should not observe such uniform powers of rapid locomotion in 
wild herds of mammals and wild flocks of birds. Consequently a large 
part of the elaborate tables of variation signify little except that there is 
an incessant change of 'proportion in every hone of the body from birth to 
death, some of which is adaptive, some* accidental or fortuitous, some 
really hereditary and significant. Nor is there any single part of the 
skeleton which can be taken as a norm or base by which other parts 
can be measured. This is not inconsistent with the fact that skeletal 
indices and ratios based on animals of the same sex and same age may 
constitute excellent subspecific and specific characters, and may also 
be much more reliable in definition than the present descriptive terms 
‘Tonger,” ‘‘shorter,” “broader,” “deeper,” etc. As good a definition 
of a race, of a subspecies, or of a species, as any other, would be a num- 
ber of its indices and ratios taken from different parts of the skeleton. 
It appears that direct measurements are profoundly altered by gigan- 
tism and dwarfing, but indices and ratios remain the same. Again 
Allen (1887) has led the way by applying the method of ratios in his 
discussion of the skeletal characters of Monachus in comparison with 
three other phocids. In his paper on M. tropicalis^^ he presented com- 
parative ratios for the skull (pp. 11, 12, with table), skeleton and limb 
segments (pp. 12-17) with important and suggestive results. 
CONCLUSION 
In this paper I have pointed out only a few of the many resemblances 
and contrasts between zoologic and palseontologic research in mam- 
malogy. The palaeontologist who does not study living mammals is 
out of date; the modern palaeontologist is constantly studying living 
mammals to supplement his limited material in tooth and bone and to 
check his constructive imagination as regards habits and habitat. 
The zoologist who does not study fossil mammals fails to perceive some 
of the most fundamental processes of mammahan evolution. For by 
a strange paradox, which I have pointed out many times, every char- 
acter in a living mammal appears to be static or in a state of rest,^^ 
Allen, J. A. The West Indian Seal {Monachus tropicalis Gray) . Bull. Amer. 
Mus. Nat. Hist., vol. II, pp. 1-34, April, 1887. 
25 ‘‘Within historical times we have absolutely no evidence of serious evolu- 
tionary change. A system that would have sufficed for three thousand years in 
the past will probably do for an equal time in the future. By the time evolu- 
tionary change introduces serious disturbance in the present scheipe of things 
it is probable that our whole classification system will have been scrapped for 
something better or else altered beyond recognition.” — P. A. Taverner: The Test 
of the Subspecies. Jour. Mamm., vol. I, no. 3, p. 125, May, 1920. 
