88 REPORT OF NATIONAL MUSEUM, 1921. 
masses of molybdenum ore has recently been installed, and an in- 
structive addition made by Mr. Shannon to the economic series in 
the form of weighed samples of some of the more important ores, 
each of which is accompanied by samples of its constituent elements 
in their relative portions. The saline series has been greatly im- 
proved by the addition of materials collected in California by Mr. 
Foshag. To make space for a collection of ores from Argentina, a 
series of mercury-antimony ores from Huitzuco, Mexico, was removed 
from exhibition. 
Information sufficient for the disposition of some 250 boxes of mis- 
cellaneous material stored for the Geological Survey in the summer 
of 1919 having been received from the Director, the task of assorting 
them was undertaken and carried out so far as the identity of the 
boxes could be definitely determined. This proved both tedious and 
difficult owing to careless and incomplete labeling. A part of the 
boxes were returned to the survey, some turned over to various sur- 
vey men located in the National Museum, and 128 boxes were acces- 
sioned as a transfer. Of the last named but a small proportion has 
as yet been unpacked. The work goes slowly since much of the ma- 
terial is in such a condition that the disposition of each lot requires 
careful consideration, and in many cases can not be made without 
thorough investigation and consultation with the survey collectors. 
Where decision is possible the material has either been rejected as 
unsuitable for museum purposes or has been catalogued and incorpo- 
rated in the collections. 
Two cases supplementing the collection of gems have been added to 
the exhibits in the mineral hall. One of these contains gem minerals 
in the matrix or as found in nature; the other illustrates the varieties 
and occurrence of precious opal. 
Incidental to the visit of Madame Curie the exhibit illustrating 
radio-activity was materially enlarged and reinstalled in two cases 
at the east end of the mineral hall, where it is more attractive as well 
as more instructive than as formerly displayed. 
The study series of minerals has been entirely overhauled, cleaned, 
and rearranged. A number of specimens were transferred to other 
series, and the drawer labels improved to facilitate the ready location 
of specimens. The duplicate collection has likewise been overhauled 
and a large amount of worthless material discarded. Several hun- 
dred petrographical specimens selected from old sets broken up have 
been incorporated in the study series of rocks. 
The great influx of new collections to the section of invertebrate 
paleontology has required continued rearrangement of the study 
series in order to accommodate the new material. Much time has to 
be spent each year in this purely manual labor, but condensation and 
elimination of duplicates is necessary since the collections at present 
