0. C. Marsh on Cretaceous and Tertiary Birds. 205 
the vacuum obtained at the beginning and end, on the perfect 
combustion, and on the perfect transfer of the gas. 
In conclusion I would present my grateful acknowledgments 
to Dr. W. Gibbs, to whose kindness I am indebted for the selec- 
tion of my subject, for the use of materials, and for many yal- 
uable suggestions during the prosecution of my wor 
Cambridge, Jan., 1870. 
See 
Art. XX V.— Notice of some Fossil Birds, from the Cretaceous and 
Tertiary Formations of the United States; by O. C. Marsu, 
Professor of Paleontology in Yale College. 
Gaudry, A. Milné-Edwards, and other paleontologists. In this 
country, however, since the discovery that the three-toed foot- 
bably 
Py Dinosaurian reptiles, no species of birds have been included 
in our extinct fauna, as, with this apparent exception, none have 
been described from any North American strata. Recent ex- 
Plorations, however, have shown that remains of this class are 
ot wanting in the later formations of the United States, and 
deposits ; but, fortunately, those parts of 
he preserved are oapeckal characteristic, so that even sm 
e specimens : 
preliminary notice, although nearly all tary are in 
excellent state of shee and most of them show strongly 
‘ : 
ae be correct, they prove the existence, In this country, aye 
Ore the close of the Mesozoic, of an in 1 si 
Stoup of aquatic birds, and suggest for this period a very m 
avine fauna. : 
