Lull — Development of Vertebrate Paleontology. 217 



assistants and in stimulating them in their productive- 

 ness so that their combined results form a very consider- 

 able share of the later literature in America. 



The ninth decade ushered in the work of a valuable 

 group of students, of whom John Bell Hatcher should be 

 mentioned in particular, as his work is done. Graduate 

 of Yale in 1884, he spent a number of years assisting 

 his teacher, Professor Marsh, mainly in the field, collect- 

 ing during that time, either for Yale or for the United 

 States Geological Survey, an enormous amount of very 

 fine material, especially from the West, although he also 

 collected in the older Tertiary and Potomac beds near 

 Washington. • In the West he secured no fewer than 

 105 titanothere skulls, explored the Tertiary, Judith 

 River, and Lance formations, collected and in fact vir- 

 tually discovered the remains of the Cretaceous mammals 

 and of the horned dinosaurs which he was later privileged 

 to describe. He then (1893) went to Princeton, which he 

 served for seven years, his principal work being explora- 

 tions in Patagonia for the E. and M. Museum, one direct 

 result of which was the publication of a large quarto on 

 the narrative of the expedition and the geography and 

 ethnography of the region. Going to the Carnegie 

 Museum in Pittsburgh in 1900, Hatcher carried forward 

 the work of exploration and collecting begun for that 

 institution by Wortman, and as a partial result prepared 

 many papers, the principal ones being memoirs on the 

 dinosaurs Ilaplocanthosaurus and Diplodocus. In 1903, 

 with T. W. Stanton of the United States Geological Sur- 

 vey, Hatcher explored the Judith River beds and together 

 they settled the vexatious problem of their age, the 

 published, results appearing in 1905, after Hatcher's 

 death. His last piece of research, begun in 1902 and 

 continued until his death in 1904, was an elaborate mono- 

 graph on the Ceratopsia, one of the many projected by 

 Marsh. Of this memoir Hatcher had completed some 

 150 printed quarto pages, giving a rare insight into the 

 anatomy of these strange forms. The final chapters, 

 however, which were based very largely upon Hatcher's 

 own opinions, had to be prepared by another hand. 



Despite his early death, therefore, Hatcher rendered 

 a very signal service to American paleontology — in 

 exploration, stratigraphy, morphology, and systematic 

 revision — and his activity in planning new fields of 

 research, such, for instance, as the exploration of the 



