16 Othniel Charles Marsh. 
to refer them to the Jurassic, a formation which had been con- 
sidered as absent in eastern North America. 
There yet remains for consideration the real work of his 
life,—his publications on the Fossil Vertebrates, and it is at 
once evident, from a glance at the bibliography, that his chief 
researches were upon the Reptiles, Birds, and Mammals. 
There are three papers on Fossil Fishes, containing notices of 
several new forms, but no real research in this class was ever 
undertaken by him. The Amphibians also claimed but little 
attention, and his observations on the metamorphosis of the 
recent Szredon into Amblystoma, and two brief notices of 
amphibian footprints in the Devonian and Carboniferous, com- 
prise the whole. 
It is with extreme hesitation and a sense of inadequacy that 
the writer ventures to review, even in the briefest and most 
superficial manner, the work which undoubtedly constitutes 
the literary essence of his life-work. Future investigators 
alone can critically estimate the great mass of facts which 
Marsh brought out and which he wove into the departments 
of fossil Reptiles, Birds, and Mammals. 
His most comprehensive work, and in many ways the most 
masterly, is the address delivered before the American Asso- 
ciation for the Advancement of Science, at Nashville, in 1877. 
In this paper, entitled the “Introduction and Succession of 
Vertebrate Life in America,” he traced the introduction of the 
various types of vertebrate life then known in America, begin- 
ning with the lowest fishes and ending with man. The amount 
of knowledge on the lower classes of vertebrates, including the 
reptiles, was then too meager to enable him to give more than 
occasional hints as to their phylogeny. But his handling of 
the Mammalia showed the clearest insight into the develop- 
ment and affinities of many of the important types, and marked 
him as a true philosopher. 
A glance at the modern text-books of Geology and Paleon- 
tology reveals how much America has done for the fossil ver- 
tebrates in the three classes of Reptiles, Birds, and Mammals. 
It will also show that Marsh contributed more than any other 
investigator toward the prominence now accorded to the 
American forms. 

