18 Othniel Charles Marsh. 
The acquisition of a unique specimen of Pterodactyl from 
the lithographic slates of Bavaria enabled him to supply the 
long sought information regarding the wing and caudal mem- 
branes. Notices of a number of new species of fossil Croco- 
diles, Lizards, and Turtles, complete this survey of his work on 
the Reptilia. 
Practically, most of the present knowledge of extinct bird- 
life in America is contained in Marsh’s publications, which 
include descriptions of numerous species, ranging from the 
Jurassic to the Post-Pliocene. Unquestionably, the one dis- 
covery which is always foremost in men’s minds in a considera- 
tion of his work is the determination of an extinct order of 
birds possessed with teeth. The study of the Dinosaurs and 
Toothed Birds showed that one by one characters considered 
as avian were likewise present in reptiles, and that many rep- 
tilian characters were present in these primitive birds ; so that 
at the end there did not seem much else besides feathers to 
distinguish them. Marsh’s investigation of fossil birds led to 
the publication, in 1880, of his first monograph, “ Odontor- 
nithes: a Monograph on the Extinct Toothed Birds of North 
America.” In this volume, he carefully figured and described 
all the known types, and presented complete restorations of the 
two leading genera, Hesperornis and Ichthyornis. He con- 
cluded that birds most nearly resemble some of the small 
Dinosaurs from the American Jurassic, and that both classes 
originated at least as far back as the Trias or late Paleozoic, 
in some sauropsid type. 
A discovery which rivaled that of the Toothed Birds, 
although not so wholly his, was the genealogy of the Horse. 
Huxley and Kovalevski traced the equine branch through the 
Pliocene to the Upper Miocene in Europe, but the true and 
remote ancestry remained unsolved until the American types 
were described by Marsh. He showed that a primitive and 
diminutive polydactyl horse existed in the Lower Eocene, and 
that from this type, by gradual and progressive change through 
successive horizons of the Eocene, Miocene and Pliocene, 
there had been evolved all the intermediate stages leading to 
the modern horse. 3 
Next in importance and interest should be noticed the series 
of papers culminating in the monograph of the Dinocerata, 

stag Se he —e Se ‘.<: - sia 
ee ee ee ee eS a i ees 
Pe 
+o —— ——— 
s 
an see ts A 
es 
at ae 
