242 Prof. Silliman’s Address before the 
enable us, in like manner, to restore their skeletons—when, with- 
out doubt, they will be found to be appropriate companions of 
the gigantic frogs of their day—not more acceptable however, 
we may presume, in their regal sway, than were the storks of 
fabulous narrative, when appointed by Jupiter to reign over-the 
frogs of that epoch of comparative pigmies. We want nothing 
but the fossilized bones of these primeval birds, to establish their 
existence ages before the earliest period heretofore assigned to 
them in the tertiary, or very recently in the Wealden, above the 
oolite and below the chalk, by Dr. Mantell. 
The gigantic birds and frogs would be also in perfect keeping 
with the colossal reptiles, the Ichthyosauri, Plesiosauri, Megalo- 
sauri and Iguanodons of that middle reign, the fit successors of 
the great Saurian fishes below the coal, as they were, in their 
turn, successors or companions of the carnivorous cephalopods of 
the Silurian rocks. 
DESIDERATA AND DIFFICULTIES. 
In speaking of the desiderata of American geology, I have only 
to refer to the mention already made of the deficiencies in out 
geological table. If those members of the geological series, in 
which we are deficient, do really exist within our territories, 
(giving them their widest range to the Pacific Ocean,) or, if they 
- even in any part of North America, it is most desi 
that they should be discovered, for our boundaries in science are 
not limited by political divisions. There is much remaining yet 
to be done in this country, and in all countries, even those that 
have been most explored; and the number of well instructed . 
geologists is now so considerable in all enlightened communities, 
that the great work will assuredly go forward with ceaseless 
effort and with increasing success, presenting rich additions to 
our knowledge and giving still greater precision and extension 10 
our scientific views. 
has now survived most of its difficulties. 'To exam 
iaeeahs » structure of this earth is no longer regarded as a vai, 
idle, OF presumptuous pursuit. Its economical utility is admitted 
bei in our public counsels, who neither perceive N0F 
. e its high intellectual and moral interest, while the po 
_ OPposition is gradually yielding to the force of truth and 
le sanasles of criticism mand oeaieige pple! 
