CARBONIFEROUS AGE. 



327 



scar from a modern species (resembling that figured near the middle 

 of the sketch, page 322), in Fig. 629 A, — all half the natural size. 

 The trunks of Tree-ferns consist within of vertically plicated woody 

 plates, with more or less cellular tissue between, and not of concentric 

 rings. The twisted plates are well shown in a transverse section of 

 a fossil trunk from the Coal-measures. 



Figs. 634-641. 



Figs. 634, 634a, Neuropteris Loschii, parts of same leaflet: 635, Nemopteris hirsuta; 636, Pecop 

 tens arborescens ; 636 a, a portion of the same, enlarged ; 637, Cyclopteris elegans ; 638, Aste- 

 rophyllites OTalis, with the nutlets in the axils of the leayes ; 639, A. sublevis ; 640, Sphe- 

 nophyllum Schlotheimii ; 641, Calamites cannaeformis ; 641a, surface-markings of same, en- 

 larged. 



The variety of Ferns was very large. Some of the more common 

 forms are shown in Figs. 630 to 633, and still others in Figs. 634 to 

 637. 



3. Equiseta or Horsetails. — The prominent genus of Equiseta was 

 Calamites, as in the Devonian. One of the jointsd stems is rep- 

 resented in Fig. 641. 



