528 PROCEEDINGS OF THE WASHINGTON MEETING 



this group. In other groups of aquatic reptiles he also brought out uew 

 genera and types of structure. Prominent among these may be mentioned 

 Baptanodon, a toothless ichth yosaurian. Marsh was the first to describe 

 the remains of fossil serpents in the western Tertiary deposits, and likewise 

 the first to discover the remains of flying reptiles in America. The 

 latter were of unusually large size and remarkable for the absence of 

 teeth. 



The acquisition of a unique specimen of pterodactyl from the litho- 

 graphic slates of Bavaria enabled him to supply the long sought infor- 

 mation regarding the wing and caudal membranes. Notices of a number 

 of new species of fossil crocodiles, 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 descrip- 

 tions of numerous species, ranging from the Jurassic to the Post-Plio- 

 cene. Unquestionably the one discovery which is always foremost in 

 men's minds in a consideration 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 reptilian 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 investi- 

 gation of fossil birds led to the publication, in 1880, of his first mono- 

 graph, " Odontornithes : 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 restoration of the two 

 leading genera Hesperornis and Ichlhyomis. He concluded 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 rivalled 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. 



Next in importance and interest should be noticed the series of papers 

 culminating in the monograph of the Dinocerata issued in 188G by the 

 United States Geological Surve}^. His work in other groups of mam- 



