X. 



LEPIDODENDREAE. 



THE family of Lepidodendreae is one of the most conspicuous among 

 those vegetable types which have become extinct in the course of geological 

 times. Like most of these types, it culminates in the Carboniferous period, 

 attaining its greatest development in the lower and middle divisions of the 

 Coal-measures l . Soon after that period it disappears, some scanty remains 

 only being known from the Rothliegende. The furthest point to which the 

 group can be followed in the other direction is the lower portion of the 

 Devonian system, to which the schists of Wieda in the Harz are considered 

 to belong. These beds have produced two indubitable remains of Lepido- 

 dendron, which were originally described by A. Romer 2 and have been 

 submitted by Weiss 3 to renewed and thorough examination. It is very 

 doubtful whether the two older Silurian remains, Protostigma sigillarioides 4 

 from the Cincinnati group of the Middle Silurian deposits and Glyptoden- 

 dron eatonense 5 from the Clinton Limestone which forms the base of the 

 Upper Silurians, belong to Lepidodendreae. I must refer the reader to the 

 original publications for an account of these forms. 



We are acquainted with a large number of stems, branches, leaves, and 

 fructifications of Lepidodendreae, which are proved beyond doubt to have 

 belonged to one another by having been found attached to one another. 

 And if the group is here brought into immediate connection with Lycopo- 

 diaceae, the reason for this arrangement is to be found not merely in the 

 habit of the organs of vegetation, but chiefly and emphatically in the struc- 

 ture of the cones of the fructification, which have been very carefully 

 studied and which positively exclude a closer alliance with any other 

 family. We shall return to this subject, as well as to the anatomy of the 

 organs of vegetation, in a subsequent page. 



The surface of the stem when well preserved, as it very often is, pre- 

 sents a highly characteristic appearance, and hence Lepidodend.rae came to 

 be noticed by authors as early as the eighteenth century, by Volkmann 



1 Grand' Eury (1). a A. Romer (l;. v. ' Weiss (3), t. 6, p. 168. 4 I.esquerenx (5). 



5 Claypole (1). Volkmann (IX 



