286 STRATIGRAPHICAL GEOLOGY 



on a later page. The correlation of the two sets of stages is given 

 below. 



Upper Coal-measures with Fourth flora. 



Transition Coal-measures ,, Third flora. 



Middle Coal-measures ,, Second flora. 



Lower Coal-measures"! ,,. , a 



Millstone grits ) " Fnst flora ' 



B. LIFE OF THE PERIOD 

 1. The Fossil Flora 



a. Equisetales. Calamites were gigantic Equiseta or horse- 

 tails, and consisted of a large hollow pith cavity encased in a thin 

 cylinder of woody tissue. The central part has generally been 

 filled up with mineral matter, forming the casts which are such 

 common Carboniferous fossils. The outer ligneous envelope, being 

 carbonised and friable, is seldom preserved in a perfect state. 



The name Calamites is at present restricted to these jointed 

 stems, while other names, Asterophyllites and Annularia, are given 

 to different varieties of foliage which belonged to Calamites. The 

 fruit is a scaly spike (Calamostachys and Palceostachya), in which 

 sporangia are arranged like those of Equiseturn. 



Sphenophyllum is the foliage of a plant related to Calamites, 

 but is now known to differ in several respects, and the fruit is a 

 whorled sporophyll resembling that of the recent genus Psilotum. 



Calamodendra are casts of the central cavity or pith of plants 

 resembling Calamites, but having a thick woody outer coating or 

 bark. Calamodendron thus appears to have been a highly developed 

 Equisetum. 



6. Lycopodiales. Lepidodendra were gigantic members of 

 the Lycopodiales, or Club-moss family, having trunks many feet in 

 girth and 40 to 60 feet in height. The trunks branch toward 

 the top into several limbs, which divide again into smaller boughs. 

 The foliage consists of simple linear leaves, which are sometimes 

 found attached to the terminal branches (Fig. 96), and the angular 

 scars on the stem are the marks left by the detachment of these 

 leaves. Ulodendron, Lepidophloios, and Halonia are allied genera. 



The scaly cylindrical bodies which are known as Lepidostrobi 

 are the cones which contain the sporangia or seed-cases of the 

 Lepidodendra, and were borne at the extremities of some of the 

 branches. 



Sigillaria. These appear to have been the commonest trees in 

 the swampy portions of the Carboniferous forests, and have 

 evidently supplied the chief mass of the material which forms our 



