20 



shadowing oar present avian fauna. The extinct genera are the 

 Eocene Uintornis, related to the Woodpeckers, and Aletornis, 

 which includes several species of Waders. Among the existing 

 genera found in our Tertiary beds are, Aquila, Bubo, Meleagris, 

 Grus, Graculus, Puffinus, and Catarractes. The Great Auk 

 (Alca impennis), which was once very abundant on our North- 

 east Coast, has become extinct within a few years. 



In this brief summary of the past life of Eeptiles and Birds 

 in America, I have endeavored to exclude doubtful forms, and 

 those very imperfectly known, preferring to present the conclu- 

 sions reached by careful study, incomplete though they be, rather 

 than weary you with a descriptive catalogue of all the fossils 

 to which names have been applied. Even this condensed 

 review can hardly fail to give you some conception of the 

 wealth of our continent in the extinct forms of these groups, 

 and thus to suggest what its actual life must have been. 



Although the Trias offers at present the first unquestioned 

 evidence of true Reptiles, we certainly should not be justified 

 in supposing for a moment that older forms did not exist. So 

 too in consideiing the different groups of Reptiles, which seem 

 to make their first appearance at certain horizons, flourish for 

 a time, andtheu decline, or disappear, every day brings evidence 

 to show that they are but fragments of the unraveled strands 

 which converge in the past to form the mystic cord uniting all 

 life. If the attempt is made to follow back any single thread, 

 and thus trace the lineage of a group, we are met by difficulties 

 which the science of to-day can only partially remove. And yet 

 the anatomist constantly sees in the fragments which he studies 

 hints of relationship which are to him sure prophecies of future 

 discoveries. 



The genealogy of the Chelonia is at present unknown, and 

 our American extinct forms, so far as we now have them, 

 throw little light on their ancestry. This is essentially true, 

 also, of our Plesiosauria, Lacerlilia and Ophidia, although sug- 

 gestive facts are not wantiug to indicate possible lines of 

 descent. With the Crocodilia, however, the case seems to be 



