114 HISTORICAL GEOLOGY 



the historical sub-division the species arc arranged according to their posi- 

 tion in the scale of life that IS, following a biological classification, the 



lower or simpler forms being placed first. The diamond-shaped bits of 

 emerald green paper attached to some of the specimens indicate those, more 

 than 8,000 in number, known as "types" or "figured specimens," used by 

 James Hall, H. P. Whitfield and others in the original description and 

 naming of species or in their elucidation. 



The upper shelves and the ends of the upright cases contain particularly 

 large or striking specimens of fossils, or blocks of rock illustrating the geolo- 

 gical features of the horizons in which the fossils occur. 



Attention may be called also to the collection of Michigan copper ores, 

 orbicular granites and diorites from several parts of the world, fossil crinoids 

 from Waldron and Crawfordsville, Indiana, fossil corals from the Devonian 

 reefs near Louisville, Kentucky, fossil crinoids and an immense clamlike 

 shell from the Cretaceous of Nebraska, fossil plants from Tertiary beds at 

 Florissant, Colorado. The windows contain some colored transparencies 

 from photographs of interesting scenery in the West. 



[Return to the Hall of Mastodons and Mammoths and turning to the right 

 enter the West Corridor or Gem Hall.] 



