64 EEPORT OF NATIONAL MUSEUM, 1918. 



to be occupied.. It became necessary, however, in February, to close 

 the hall devoted to the exhibition of dynamic and structural geology, 

 and the exhibit was placed temporarily at the west end of the main 

 hall of the section of vertebrate paleontology in preference to storing 

 it. The map showing the known meteorite falls was brought up to 

 date in October. 



Two stereomotorgraphs, fitted with slides illustrating such phe- 

 nomena as could not readily be shown by specimens, were installed 

 on the first and second floors in connection with the exhibits. 



Four slope-top cases filled with exhibits of a more or less tem- 

 porary nature, made up largely of new accessions, were added to the 

 mineral hall. The cases containing the systematic mineral series 

 were given a thorough cleaning. 



An entirely new biologic series of brachiopods, installed in two 

 large cases, contains not only the specimens, but- models, photographs, 

 and drawings, designed to show the embryology, anatomy, and evolu- 

 tion of this class. The exhibit of fossil corals, hitherto inadequate to 

 properly illustrate this important group, was increased to three 

 times its former size by the addition of large, showy specimens col- 

 lected in recent years especially for exhibition purposes. Another 

 important addition was the introduction into both the stratigraphic 

 and biologic series of over 100 photographs of fossils and other 

 illustrations. 



The exhibits have been further increased by -the installation of 

 four large specimens illustrating various kinds of conglomerates, 

 two specimens showing extremes in growth methods of Algonkian 

 calcareous algae, and a large slab showing stratigraphic uncon- 

 formity. The coral reef installed the previous year was enlarged 

 by the addition of several layers of limestone and shale, so that in 

 this one exhibit the phenomena of stratification, change of lithology, 

 and occurrence of fossils are illustrated. 



Two of the larger cases in the paleobotanical hall were remodeled 

 and new exhibits illustrating pre-Carboniferous plants installed. 

 The large fossil tree stump preserved in sandstone, from the Coal 

 Measures of Kentucky, mounted temporarily last year, was placed 

 on a permanent base and forms a very showy and instructive exhibit. 

 Over 500 new labels, combining scientific data with more popular 

 information, easier of comprehension by the public, replaced the old 

 ones with the paleobotanical exhibit. 



When the halls were in such condition that they could be con- 

 sidered of the highest educational value, war necessities re- 

 quired the allotment of the space to the Bureau of Wa:- Risk In- 

 surance. The space devoted to the penological exhibit was vacated 

 for that purpose in February, and that collection is no longer ac- 

 cessible to visitors. Near the close of the fiscal year the halls de- 



