INTRODUCTION. 
XX111 
guano, it might have been that at that time the decomposition of the 
remains, through the corrosive nature of the excreta, is the reason 
why fossil bird-bones are so rarely discovered. 
“ These primitive Penguins were followed, then, in the further course 
of the fletz period, by gigantic swamp birds, which have written with 
their feet, on the geological records of Nature, indelible evidences 
of their existence; while their bones, together with those of their 
earlier predecessors, have disappeared. The indelible foot-marks 
found on the primary strata of the Trias group remind us of mighty 
Jabirus and gregarious Storks. 
“The more extensive development of vegetation rendered the 
existence of tree-birds a possibility, and a primaeval type of Wood¬ 
pecker, Thrush, Crow, and Fish Hawk were created, so as, in a 
certain degree, to produce a primitive legitimate balance amongst the 
worms, insects, and fish. When, during the tertiary period, vegetation 
continued to expand, and, reaching a higher state of organization, 
divided itself into endless types,—Waterhens, Rails, Partridges, Wood 
Grouse, as well as a mighty family of Ostriches, appeared on the most 
recent raft-like floating masses of the earth’s crust, and completed 
the forms of the primitive progenitors of the bird-world; on the 
other hand, in contradistinction to the Penguins, these later forms, 
losing their powers of flight, were annihilated by the Deluge. 
“We have now, however, seen these primitive types of birds 
develope themselves in a manner that may be compared to the 
different progressive ages of an individual: for the Penguin, by 
reason of its fin-shaped rudimentary wings, remained in the grade 
of the imperfectly-fledged nest-bird, so to speak; the Herons and 
Storks, moulting almost the whole year round, resembled the 
fledgling; while the Woodpecker, Thrush, Crow, and Fish Hawk, 
acquired maturity ;•—thus predicting a perfecting of the powers 
of flight, amongst birds frequenting trees and the regions of 
the air. At last we approach the diluvial epoch: we find aquatic 
birds represented by Waterhens, Rails, and gallinaceous birds, 
confined in their means of locomotion to the earth’s surface; also 
immense running birds, like the Ostriches;—all seem to lose the gift 
of flight; thus, as it were, becoming aged, turning into the ‘ lean 
and slippered pantaloon,’ so to speak, of the bird-world,—a poor 
reflection, in fact, of the power of the bird in mid-air, such as is 
possessed by the Eagle; thus, appearing to us as a passing link in 
