. 
256 Marsh’s Monograph on the Odontornithes 
beds, and of having published all the original matter that has 
yet.been brought out on the American Odontornithes. 
The present work, which appears as volume VII of the Sur- 
vey of the 40th Parallel, is also the first of the Memoirs of the 
Peabody Museum of Yale College. It contains, in its Preface, 
an outline of the plan of the series to be issued, of which this 
is the initial volume; and as this subject is one of general 
interest to paleontological science, we cite the following para- 
graphs. 
“The present volume is the first of a series of monographs 
designed to make known to science the Extinct Vertebrate 
Life of North America. In the investigation of this subject, 
the writer has spent the past ten years; much of it in the field, 
collecting, with no little hardship and danger, the material for 
study, and the rest in working out the characters and affinities 
of the ancient forms of life thus discovered. 
“During this decade, the field work, extending from the 
Missouri River to the Pacific Coast, has so predominated, as 
the subject unfolded, that a plan of gradual publication be- 
came a necessity. The more important discoveries were briefly 
announced soon after they were made, but only where the 
specimens on which they were based could be accurately de- 
results already attained are full of promise for the future. A 
somewhat careful estimate makes the number of new species 
of extinct vertebrates, collected since 1868, and now in the 
Yale College Museum, about 1,000. Nearly 300 of these have 
already been described by the writer, and some have been 
noticed or described by other authors, but at least one-third 
remain to be investigated. 
‘Among the new groups brought to light by these re 
searches, and already made known by descriptions of their 
principal characters, are the following, which will be fully de- 
scribed in subsequent volumes of the preseut series. : 
‘The first Pterodactyles, or flying reptiles, discovered in this 
country, were found by the writer in the same geological hor 
zon with the Odontornithes, described in the present volume. 
