MKMOIR OF O. C. MARSH 527 



vancement 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, beginning 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 development 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 paleontology re- 

 veals how much America has done for the fossil vertebrates 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. 



His work on the Reptilia is not equally divided among the various 

 orders, for the Dinosauria claimed his attention above all others. To 

 this group he lent his best efforts, and he compassed it so thoroughly as 

 to be its sole master. It seems only necessary in this place to notice the 

 complete restorations he made of some of these remarkable animals. In 

 this list are included Anchisaurus, Brontosaurus, Laosaurus, Ceratosaurus, 

 Camptosaurus, Stegosaitrus, Triceratops, and Claosaurus. It must be re- 

 membered that nearly all these animals were of gigantic stature, some 

 of them the largest land animals yet known, and also that each restora- 

 tion represents a number of separate investigations on the structure of 

 the skull, the limbs, the vertebrae, the pelvis, etcetera. In most cases 

 only by this means was it possible *to bring together gradually, part by 

 part, until the sum of the knowledge warranted a complete representa- 

 tion of the skeleton. The material of many of the genera he described 

 is still in these various stages of progress, awaiting new additions of 

 portions yet unknown in order to form a finished conception of the entire 

 animal. His extensive report on the Dinosaurs of North America, pub- 

 lished in 1896, gave a synopsis of what he had accomplished up to that 

 time; but as remarked elsewhere their philosophical treatment he had 

 reserved for his final monographs. 



Probably among the Reptilia next in importance to his work on the 

 Dinosauria is that on the Mosasaurs. In this he first announced the dis- 

 covery of the dermal armor, the position of the quadrate, the finding of 

 the stapes, the columella, the hyoid, the sclerotic plates, the quadrato- 

 parietal arch, the malar arch, the transverse bone, the pterygoids, the 

 pterotic bone, the sternum, the anterior limbs, the posterior limbs, the 

 length of the neck, and details of the pelvic region. Thus he contributed 

 a knowledge of some of the most essential characters of the skeleton in 



LXXV— Bull. Geol. Soc. Am., Vol. 11, 1899 



