SECRETARY'S REPORT 3 



remaining collections in tliis, as in all fields, are available for study 

 by qualified students. 



2. FOSSIL FISHES AND AMPHIBIANS 



The Hall of Fossil Fishes, Amphibians, and Primitive Eeptiles 

 displays selections from the Smithsonian's superb collections of these 

 fossil creatures wliich represent the most primitive groups of back- 

 boned animals. Here are many actual skeletons of some of these great 

 ancient animals that ruled the land and the seas before modern ani- 

 mals evolved. This hall portrays in a particularly clear way the 

 development of jaws and tlie anatomical changes related to the transi- 

 tion from life in water to life on the land. A habitat group illustrates 

 for the visitor what some of these animals were actually like when 

 they ranged the globe. A life-size diorama shows conflict between 

 two kinds of pelycosaurs, or fin-backed reptiles, as might have hap- 

 pened 260 million years ago. 



3. PREHISTORIC MAMMALS 



In the Hall of the Age of Mammals in Xorth America lifelike 

 dioramas and scientifically accurate and artistically significant murals 

 recreate a mammalian world that existed before modern man ap- 

 peared. Here are shown skeletons of some of the marine and land 

 mamimals that swam, climbed, ran, or even flew millions of years ago. 

 To give but one example, in a well-lighted case is the complete fossil 

 skeleton of a 55-foot-long primitive whale. The remarkable series of 

 skeletons exhibited in this hall were painstakingly collected by Smith- 

 sonian scientists in the field over many years and were then skillfully 

 prepared for disjjlay in the museum laboratory of the Institution. 



4. GEMS AND MINERALS 



The Smithsonian Institution has one of the world's great collections 

 of minerals. Competent observers declare that the Smithsonian's 

 new Hall of Minerals is the best single exhibition of its kind in the 

 world. The immediately adjacent Gem Room is also spoken of as 

 the best exhibition of gems on public display in the United States. 

 Thousands of specimens, many of them of great rarity and beauty, 

 are featured in cases at an ideal height and so lighted as to show 

 colors properly. The galleries are arranged so that the student of 

 mineralogy can learn about both the crystalline structures of min- 

 erals and the chemical composition of the specimens displayed. But 

 the hall is also significant from an esthetic and natural-history point 

 of view for persons interested in minerals and gems as beautiful ob- 

 jects rather than as basic specimens for the science of mineralogy. 

 One dramatic case shows selected minerals imder ultraviolet light, 

 which causes them to fluoresce with glows of many dijfferent colors. 



