CARBONIFEROUS SYSTEM. 65 



to various portions of our sea-shores, as those of 

 South Wales, Lancashire, Northumberland, and 

 various parts of Scotland. This formation consists 

 of the coal measures, deposits of ironstone, mill- 

 stone grit, and limestone, exhibiting great variety 

 of hue and quality. The organic remains peculiar 

 to it are very numerous, and of great interest. 



The fossil plants of this system are extremely 

 characteristic : they constitute the entire mass of 

 those deposits of coal which are of such surpassing 

 value to mankind ; they are likewise thickly inter- 

 spersed throughout the other formations belonging 

 to the carboniferous system, and are, as may be 

 presumed, of great interest to the student of fossil 

 botany. Without discussing the many interesting 

 questions which suggest themselves on the subject 

 of the structure and other peculiarities of the plants 

 of the era to which the coal deposits belong, we can 

 only point out a few examples of those plants. 

 Many of the plants were evidently similar in bota- 

 nical character to the equisetum or mare's-tail, so 

 common in all our marshes at the present day ; but 

 these calamites were of gigantic dimensions ; exist- 

 ing plants of this species are little more than a foot 

 and a half in height, and their stems about a quarter 

 of an inch in diameter. The stems of the fossil 

 specimens, on the other hand, are often fourteen 

 inches in diameter, and thirty feet in length. 

 The common fern is also an example of another 

 numerous family of plants which flourished during 

 the carboniferous period. These were Sigillarise or 

 tree-ferns such as belong at present to the torrid 

 F 



