
LHE 
AMERICAN NATURALIST 


VoL. XXXVI. October, 1902. No. 430. 




HISTORICAL EVIDENCE AS TO THE ORIGIN OF 
THE PAIRED LIMBS OF VERTEBRATES. 
BASHFORD DEAN. 
WHATEVER be the results of embryologists, the real test of 
the problem of the mode of origin of the paired limbs of verte- 
brates belongs obviously to paleontology. For if the paired 
limbs, as most morphologists believe, arose as highly specialized 
lappets of a continuous lateral skin fold, it is quite evident 
that sooner or later these conditions will be demonstrated 
convincingly among the earlier fossil fishes. In point of fact, 
the paleontological evidence bearing upon this matter is of 
such great value, even at the present time, that we can justly 
regret that it has received scanty attention at the hands of 
embryologists. It is indeed so imperfectly noticed in the 
recent voluminous papers which bear upon the general problem 
of limb origin that I have been led to the following comments. 
I. THE WEIGHT oF EVIDENCE. 
If we accept the general rule that earlier forms are of greater 
value for purposes of determining primitive characters than are 
later ones, and if we admit that a study of many genera and 
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