88 REPORT OF 13"ATlO:SrAL MITSEtJM, 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 identit}'- 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 A^arious 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 3'et 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 



