GEOLOGY AND INVERTEBRATE PALEONTOLOGY 89 



beginning at the northeast corner of the hall with the archsean rocks, which 

 are the lowest and oldest of all and contain no fossils, ad- 

 Series to vancing regularly southward along the east side through the 



H' to' , Cambrian, Ordovician, Silurian and Devonian systems, passing 

 Geology to the west side of the hall in the Devonian and continuing 



through the Carboniferous, Jurassic, Triassic, Cretaceous 

 and Tertiary. Thus far the specimens are from American localities, but 

 the northwest quarter of the hall is devoted to a synoptic series of European 

 fossils. The cases in the middle of the hall contain overflow material from 

 the sides. The American series is subdivided into geographical provinces, 

 the fossils from Xew York State and other eastern regions being placed first 

 and then the material from the Central West and beyond. Under the 

 geographical subdivision the species are arranged according to their position 

 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," which have 

 been used by James Hall, R. P. Whitfield and others in the original descrip- 

 tion and naming of species or in their elucidation. 



The upper shelves of the wall cases contain particularly large or striking 

 specimens of fossils, or blocks of rock illustrating the geological features of 

 the horizons in which the fossils occur. 



Two floor cases in the middle of the hall at the north end contain a 



series of rock specimens showing the geology of Manhattan 



Geology of I s l anc l a nd a very complete collection of the minerals found 



, , . in New York City and immediate vicinity belonging to the 



New York Mineralogical Club. 



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 CrawfordsviJle, Indiana, fossil corals frcm 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] 



