REPORT OF THE SECRETARY 39 
are nuggets of gold formerly in the numismatic collection of the 
United States Mint at Philadelphia; a collection of Bolivian tin 
minerals, in part presented and in part deposited by Mr. Jack 
Hyland; and a rare palladium amalgam from British Guiana pre- 
sented by the government of that country through Sir John Har- 
rison. Of outstanding importance for exhibition is a large group 
of fiuorite crystals thought to be the most unusual yet brought 
to public attention in America. This was presented by the Benzon 
Fluorspar Co. of Cave-in-Rock, Ill. Rare minerals from foreign 
countries were acquired by exchange, and 387 cut stones were added 
to the Isaac Lea collection of gems through the Chamberlain fund. 
Material of inestimable value to the study series in stratigraphic 
paleontology was added chiefly through field explorations by mem- 
bers of the staff. Invertebrate fossils from the Cambrian and 
Ozarkian rocks of British Columbia, from the Lower Paleozoic of 
Great Britain and the continent of Europe, from the Middle and 
Upper Paleozoic of the Central States, and from the Devonian of 
New York, all selected with the museum’s special needs in mind, are 
among the collections thus secured. Gifts and transfers added im- 
portant type specimens, as well as vast collections of Cenozoic fos- 
sils. Although purchases were necessarily few in number, a few 
excellent exhibition specimens were thus procured; exchanges added 
valuable foreign material. 
Notable among the accessions of vertebrate fossils is a series of 
shale and sandstone slabs containing tracks of extinct animals, ob- 
tained from the Hermit and Yaki trails in Grand Canyon National 
Park by Mr. C. W. Gilmore in continuation of his work of last 
year. The present collection considerably exceeds in number of 
specimens the one obtained last year, and is of unique interest in 
containing faunas from three distinct levels, through a geological 
thickness of 950 feet, and from three distinct formations. Their 
great age, variety, and excellent preservation, as well as unusual 
occurrence, are features endowing these tracks with particular value 
in throwing light upon the character of the animal life of the 
Permian period. Fossil mammal material collected in Florida by 
Dr. J. W. Gidley is of unusual value as evidence for consideration 
in working out the problem of early man in that State. 
Arts and industries —The aggregate collections in this department 
indicate a fair increase over the previous fiscal year. 
In the division of mineral and mechanical technology the most 
important accession has been the airplane Chicago, the flag plane 
during the round-the-world flight of 1924, which was transferred to 
the Museum by the War Department. The Collier trophy of the 
National Aeronautic Association, awarded annually for some out- 
standing development in aeronautics, which was presented this year 
