20 On the Fossil Plants of the genus Sigillaria. 



of the North Biddick and other specimens, is, in my estimation, quite con- 

 clusive in proving that the branches of ^igillaria originated, as in the 

 higher vegetable forms, from the axils of the primary leaves,* 



•In accordance with the preceding remarks respecting the bipartition 

 of the cuticle of Sipillaria, we are naturally led to arrange a number of 

 specimens, in the states represented by the diagrams, under three separate 

 divisions. These divisions may be severally termed corticated,, demicorti- 

 eated, and decorticated. 



The corticated division will embrace those specimens having the entire 

 cuticle preserved ; the demicorticated such as have only one of the layers 

 of this part remaining, and the decorticated those which are divested of 

 both layers. 



Corticated specimens will exhibit two different appearances according- 

 ly, as the inner or outer surface of the entire cuticle may be exposed ; 

 for instance, in the latter case we shall have leaf-scars on the ribs, but in 

 the former there will be vascular scars on broad furrows. Examples of 

 the first kind are of exceedingly rare occurrence in the North of England 

 coal-field ; nearly all that are published in the ^' Fossil Flora" from this 

 district are either decorticated or exhibit only the inner surface of one or 

 other of the two layers composing the cuticle : the figures representing 

 Sigillaria altemanSj Sig, catenulata, Sig. reniformis (Tab. 71)^ and some 

 others, may be taken as examples of the last kind. 



Demicorticated specimens are extremely difficult to recognise, on ac- 

 count of the appearance which they present being somewhat similar to 

 that displayed on the inner surface of the inner layer gf the cuticle, and 

 consequently they may resemble the kinds last mentioned. Demicor- 

 ticated specimens are also divisible into two kinds, the one having the 

 vascular scars on ribs, and the other on broad furrows, t As already sug- 

 gested, Brongniart's figures of the genus Syringodendrorij and I may also 

 add some of those given by Sternberg!}: and Lindley and Hutton as ex- 



♦ I have also observed axillary buds on several specimens of Lepidodendron, 

 — a character which completely proves that the branches of this plant have had an 

 origin similar to those of Sigillaria, and not from a division of the point of the 

 main stem at certain stages of its developement, as is generally considered. 

 Sternberg's figures of Lepidodendron aculeatum (Tab. vi. fig. 2; Tab.viii. fig. 1. 

 B. a. b.), are the only published ones known to me that exhibit these axillary 

 buds ; the fossil is merely an impression, consequently, the figures shew them in 

 the state of impressions. 



t The fact already stated respecting the occasional flexuous appearance of the 

 longitudinal strice, on the ribs of the North Biddick specimens, will in a great 

 measure shew that this character is not sufiicient to constitute a specific dif- 

 ference. 



I The specimen on which Sternberg founded his genus Syringodendron (T^b. 

 xiii. fig. 1), appears to be nothing more than a decorticated portion of Stigmaria 

 (root of Sigillaria) belonging to a part adjacent to the stock. The irregularities of 

 the furrows, and the irregular arrangement of the vascular scars of this specimen 



