—_ 
THE HALL OF FOSSIL VERTEBRATES 
South America now in the museum of the Royal College of 
Surgeons, London. Some of the skeletons are partly restored in 
plaster, indicated by a red cross (restored bones) or red lines (out- 
lines of restored parts of bones). Bones supplied from other 
specimens are marked with the catalogue number of the speci- 
men or are indicated by a red circle, if uncatalogued. 
GEOLOGICAL AGES AND PERIODS. 
Age of Man, 
Quaternary 
50,000 years 
Cenozoic 
ies Age of Mammals, 
ertiary 3,000,000 years 
Cretaceous 
~ 
Mesozoic Jurassic Age of Reptiles, 
7,000,000 years 
Triassic 
| Permian Age of Amphibians and Coal 
eat Plants, 
Carboniferous 5,000,000 years 
Age of Fishes, 
Devonian 2,000,000 years 
Silurian 
Age of Invertebrates, 
: 10,000,000 years 
Cambrian 
| Algonkian 
(No fossils) 
These estimates in years of the geological periods given in the 
accompanying table, which is arranged in descending order from 
the most recent to the most ancient time, must be under- 
stood to be merely very rough approximations. There is no 
known method of finding any exact equivalent in years of any 
geological period, although the relative length of each to each is 
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