THE CARBONIFEROUS FLORA. 



119 



relation to our modern equisetums, or mare's- tails., but, 

 as in other cases we have met with, are of gigantic size 

 and comparatively complex structure. Their stems, in 

 cross-section, show radi- 

 ating bundles of fibres, 

 like those of exogenous 

 woods, yet the whole plan 

 of structure presents some 

 curious resemblances to 

 the stems of their hum- 

 ble successors, the mod- 

 ern mare's-tails. It would 

 seem, from the manner 

 in which dense brakes of 

 these Calamites have been 

 preserved in the coal-for- 

 mation of Nova Scotia, 

 that they spread over low 

 and occasionally inun- 

 dated flats, and formed 

 fringes on the seaward 

 sides of the great Sigilla- 

 ria forests. In this way 

 they no doubt contrib- 

 uted to prevent the invasion of the areas of coal ac- 

 cumulation by the muddy waters of inundations, and 

 thus, though they may not have furnished much of the 

 material of coal, they no doubt contributed to its purity. 

 Many beautiful plants of the genera Asteropliyllitcs and 

 Annular ia are supposed to have been allied to the Cala- 

 mites, or to have connected them with the Rhizocarps. 

 The stems and fruit of these plants have strong points of 

 resemblance to those of Sphenophyllum, and the leaves 

 are broad, and not narrow and angular like those of the 

 true Calamites (Fig. 45). 



No one has done more than my friend Dr. William- 



Fig. 42. — Erect Sigillaria, standing 

 on a coal-scam (S. Joggins, Nova 

 Scotia). 



