Report of the President 59 



since it is the initial set of specimens upon which the sciences 

 of stratigraphic geology and invertebrate palaeontology were 

 built in North America. It is a great source of reference, and, 

 although incomplete, it is the standard set for Paleozoic rocks. 

 The Trustees of this Museum took upon themselves a great 

 responsibility when they purchased these specimens from 

 James Hall, for they obligated themselves to all working geolo- 

 gists to care for the specimens, not only for this generation 

 but for all time to come. Experience has proved that more 

 and better care is taken of such specimens when on exhibition 

 than when lodged elsewhere. 



The biologic and stratigraphic series, comprising some 90,- 

 000 catalogued specimens, are being rearranged according to 

 a method which enhances their value for study and exhibition 

 purposes. 



Selected specimens of the gastropods and plants of the bio- 

 logic and stratigraphic series have already been mounted on 

 tablets especially devised for this purpose. It will take two 

 men with no interruptions about two years to mount the speci- 

 mens which have already been selected. 



During March and April, the Assistant Curator, with the 

 assistance of Mr. A. Briesemeister and Mr. George Robertson, 

 constructed for Professor Osborn's Hale Lectures 

 Models and a set f s ^ x paleogeographic globe relief models of 

 North America, after outline maps supplied by 

 Professor Charles Schuchert of Yale University. So far as 

 known, this was the first attempt to represent in relief and 

 outline the ancient land surfaces of six stages in the evolution 

 of the North American continent. The various incursions of 

 the sea over the land are painted in blue on the globe surface. 

 Each stage is developed on a globe sector which has a radius 

 of three feet and three and one-half inches. Three sectors 

 form a hemisphere. The models have been placed on exhibi- 

 tion at the entrance to the hall. 



After the completion of the six paleogeographic models, 

 the relief of the ocean floors about the North American conti- 

 nent was modeled in clay on a mold of the above-mentioned 

 globe by Mr. P. B. Hill. The data were supplied by the 



