134 



THE MUSEUM. 



tory, for believing that great masses of 

 land had been exposed to the atmos- 

 phere for ages, but was only a scene 

 of life in rare and favorably situated 

 places." And when we come to con- 

 sider the remarkable features of the 

 next group of rocks, forming the car- 

 boniferous era, we have great reasons 

 for concluding that land plants to a 

 large extent did exist, and had existed 

 even during the period we have named. 

 The next series of rocks is the Car- 

 boniferous formation. It commences 

 with the mountain limestone, is of 

 great extent and thickness, and alter- 

 nates with beds of sandstone, shale, 

 and coal. The remains of corals, 

 crinoidea, and shells, in some parts 

 compose three-fourths of the mass. 

 Above the limestone commence the 

 large beds of coal, the immense forma- 

 tions of which are known to be the 

 composition of putrified vegetable mat- 

 ter, decomposed under water, and in 

 the absence of air. These rocks tell 

 strikingly of the features of the earth 

 at the time of their formation. They 

 tell us of a time when carbonate of 

 lime was formed in abundance. Next 

 we have a brief period of volcanic dis- 

 turbance; then the causes favorable 

 to so great a production of limestone: 

 dry land increases, the atmosphere is 

 charged with an unusual abundance of 

 carbonic acid gas — the material of veg- 

 etation; immense forests grew rapidly, 

 and every piece of dry land was rank 

 with foliage. From the investigations 

 of eminent naturalists, about 500 dis- 

 tinct species of plants have been dis- 

 covered in this formation, the most 

 conspicuous being the fern or bracken, 

 of which I 50 species have been found. 

 Trees of immense growth have also 

 been found; one was dug up in a quar- 



ry at Edinburg, the trunk of which 

 measured two feet in diameter, and 

 forty feet in length. 



The carboniferous formation exhibits 

 a scanty /oology: the commencement 

 shows an abundance of the mollusca 

 class, but as we get higher we find the 

 first and most simple forms of fish; 

 next we have a few specimens of in- 

 sects or "creeping things," and an in- 

 stance or two of a scorpion-like creat- 

 ure. But these insect deposits are 

 few, and may have been the result of 

 the volcanic disturbances to which the 

 world was at that time subject. The 

 insects which have been found in this 

 formation are of the frog and toad 

 class. It is generally thought that the 

 conditions which allowed of such 

 abundant terrestrial vegetation had 

 ceased at the time this formation was 

 completed. 



The next formation is the i'ci-inian. 

 Here nearly the whole of the numer- 

 ous fossils common to a previous era 

 disappear, but fish appear in abun- 

 dance. 



Next we have the Trias, in which 

 reptiles of various kinds and forms are 

 found. We find slabs marked with 

 the feet of animals, resembling the 

 impressions of the fingers and thumb 

 of the human hand. We have the 

 Enaliosaurian and the Saurian tribe, 

 marine animals of great bulk, some 

 reaching thirty feet in length. We 

 find too the Plesiosaurus, an inhabit- 

 ant of the seas, partaking in form of 

 the bird and fish, and measuring about 

 eighteen feet in length. An American 

 author has stated that the footprints of 

 about thirty species of birds have been 

 discovered in this formation. 



We then come to the Oolite. Here 

 a beautiful class of plants appears, be- 



