"e 
989 James Deane's Illustrations 
remarkable fossils. The utility of artificial nomenclature based 
ipon modifications of a single organ of the animal economy, 
appears to me to be questionable ; it is by the eye alone that 
we judge of. distinctions, it is the form and not the substance 
that we investigate. Many of these forms, it is true, exhibit 
the clearest specific characters ; but, on the other hand, many, 
equally distinct, cannot be separated and arranged by mere 
methods of classification, however ingenious, so as to convey 
to the mind positive ideas of distinction from others so nearly 
resembling them. I, of course, do not speak in disparagement 
of the opinions entertained by others who are better qualified 
to decide upon and execute a different measure, but simply 
state the difficulties always to-be encountered in any classifi- 
cation of this subject, whether artificial or natural. 
The immense magnitude of some of these footprints 18 
extremely well calculated to fill us with amazement. I have 
just spoken of a footstep fourteen inches in length ; but I have 
in my possession consecutive impressions of a tridactylous foot 
which measures eighteen inches in length by fourteen in 
breadth, between the extremities of the lateral toes. These 
stupendous vestiges were recovered by Mr. Marsh and myself 
at South Hadley Falls. - Each step will hold half a gallon 
water, and the stride is four feet. It is not possible to cob 
ceive of the grandeur and magnificent proportions of this 
tremendous bird. It was, upon the lowest supposition, four 
or five times larger than the African ostrich, and, on this basis 
could not have weighed less than six hundred pounds. In all 
probability, its weight was much beyond this estimate. Every 
step the creature took, sank deep into the stratum; and the 
substrata bent beneath the enormous load. If an ox walk 
over stiffened clay, he would not sink so deeply as did this 
mighty bird. He sustained to the feathered tribes of his day 
the relations of the ostrich to existing races, and his co'09" 
_ frame well fitted him to endure the turbulence of the era "^ 
