136 



THE GEOLOGICAL HISTORY OF PLANTS. 



relation, no doubt, to the equable climate of the period. 

 There is not much evidence that they grew with the Si- 

 gillarise in the true coal-swamps, though some specimens 

 have been found in this association. It is more likely 

 that they were in the main inland and upland trees, and 



FIG. 61. Trigonocarpum Hookeri, Daw- 

 son, from the coal-measures of Cape 

 Breton. Probably the fruit of a Tax- 

 ine tree. A, Broken specimen magni- 

 fied twice natural size. B, Section magnified : a, the testa ; 5, the teg- 

 men; c, the nucleus* d, the embryo, c, Portion of the surface of the 

 inner coat more highly magnified. 



that in consequence they are mostly known to us by 

 drifted trunks borne by river inundations into the seas 

 and estuaries. 



A remarkable fact in connection with them, and show- 

 ing also the manner in which the most durable vegetable 

 structures may perish by decay, is that, like the Cordaites, 

 they had large piths with transverse partitions, a struct- 



