HORSETAILS 201 



boughs and twigs, the latter of the utmost 

 delicacy. 



The leaves were always whorled, as in the 

 recent forms; they were either quite free from 

 one another or only united at the base; usually, 

 at least in the Coal Measure species, they were of 

 a simple and narrow form. The leaves on the 

 main stems or larger branches, were some inches 

 hi length; on the little twigs they were extremely 

 minute, but hi crowded whorls, so as collectively 

 to present a large surface to the air and light. 

 The smaller twigs seem to have hung down in 

 many cases, like the branches of a Weeping Wil- 

 low. The branches were borne at the joints of 

 the stem, in the spaces between the leaves, just 

 as in living Horsetails. In some species the 

 branches were whorled and limited to particular 

 joints of the stem; in others they occurred at all 

 the joints, but often only a single branch de- 

 veloped at each; in others again the branches were 

 few and irregularly scattered. There is evi- 

 dence that certain branches were periodically 

 shed, and it is probable that this was always the 

 case with the finer twigs; we find an analogy for 

 this in the Larch and the deciduous Swamp 

 Cypress (Taxodium distichum) among recent 

 plants. 



The cones were highly organized fructifica- 

 tions, more complex, in most cases, than those 



