OTHNIEL CHARLES MARSH 297 



by Marsh, and these men working under his instructions packed 

 the accumulated specimens on the ground and shipped them to 

 New Haven. Not until 1879 did Marsh again personally visit the 

 West, but his success in ferreting out new material was undi- 

 minished. 



Marsh was appointed Vertebrate Paleontologist on the United 

 States Geological Survey, July i, 1882. The experience gained in 

 the preceding fourteen years of investigation of the geology and 

 paleontology of the Rocky Mountain region and other parts of 

 the West peculiarly fitted him for this position, which also relieved 

 him from the personal expense attendant upon keeping parties 

 in the field, although during his connection with the Survey he 

 devoted all the salary annually received from that source to the 

 advancement of the work in hand. 



In making collections for the Survey he had two objects in view: 



" (i) To determine the geological horizon of each locality where 

 a large series of vertebrate fossils was found, and 



"(2) To secure from these localities large collections of the 

 more important forms sufficiently extensive to reveal, if possible, 

 the life history of each." 



In the first of these objects he demonstrated his belief "that 

 vertebrate fossils are the key to the geology of the western regions 

 for all formations above the Paleozoic, and that most stratigraphi- 

 cal questions can be solved by them alone" a belief not shared 

 by all paleontologists and geologists. The second object resulted 

 in the vast collections he procured through various western parties 

 exploring under his direction, for during the ten years' connection 

 with the Survey he personally visited the West only four times. 

 From the Jurassic, Cretaceous, and Tertiary formations he ob- 

 tained series of fossils of the greatest scientific value, the following 

 being especially noteworthy: 



" (i) An extensive series of gigantic Dinosaurs from Colorado 

 and Wyoming, the largest land animals known, and found only 

 in a single horizon of the Jurassic. 



"(2) A series of small primitive mammals from the same lo- 

 calities, the discovery of which was of great importance. 



