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JOURNAL OP MAMMALOGY 
THE TEST OF THE SUBSPECIES 
By P. a. Taverner 
In the Journal of Mammalogy, Vol. 1, No. 1, pp. 6-9, appears an 
article by Dr. C. Hart Merriam advocating that the amount of differen- 
tiation be used as the test of specific or subspecific status, rather than 
the generally accepted one of intergradation. It is with some trepida- 
tion that I dare take direct issue with so eminent an authority but the 
case seems so clear against the proposal and its acceptance is so fraught 
with possibilities of confusion that I feel justified in lodging a protest. 
Doctor Merriam makes much of the uncertainty of human judgment 
in estimating the probability of intergradation when direct evidence 
of it is lacking. For the sake of these minority cases where the human 
element may give varying results, he advocates the recognition of the 
amount of difference exhibited rather than the presence or absence of 
intergradation as the test for specific status; thus throwing open each 
and every case, instead of an occasional one, to the uncertainty of per- 
sonal standards of judgment. It looks like out of the frying pan into the 
fire and the choosing of the greater instead of the lesser of two evils. 
Under the one standard we have numerous cases where intergradation 
can be demonstrated and subspecific status fixed. Under the other 
all are equally uncertain. It would seem more logical to go to the other 
extreme and ascribe every difference to the specific that cannot be 
demonstrated to inter grade with others. This would however be carry- 
ing logic to an extreme and I see no real reason why we should not 
continue to rely upon the good judgment of experience to assume the 
probability of intergradation where data is incomplete, readjusting 
mistakes according to new evidence. Finality can thus be gradually 
approached even though it may never be perfectly attained. The 
occasional transference of species to subspecific status and the converse 
are not serious disturbances so long as we keep the fundamental differ- 
entiation in mind and remember that in many cases intergradation is 
hypothetical and still awaits demonstration. 
It is also more than probable that a strict adherence to the proposed 
criterion would land us in greater confusion than we experience now. 
Under it, on the evidence of specimens on which most of our conclusions 
are based, we would class the gray-cheeked and ohve-backed thrushes 
as mere subspecies whilst the extremes of such forms as song sparrows, 
fox sparrows and horned larks we would raise to full specific status. 
