180 LYCOPODIALES [CH. 



assuming a partial decortication to have occurred prior to 

 fossilisation, it may represent a gap in the cortical tissue caused 

 by the decay of delicate tissue which surrounded the vascular 

 bundle of each leaf in its course through the cortex of the 

 stem. If the impression were that of the actual surface of a 

 Lepidodendron or a Sigillaria, we should expect to find traces 

 of the parichnos appearing on the leaf-scar as two small scars, 

 one on each side of the leaf-bundle. In specimens from Veree- 

 niging described in 1897^ as Sigillaria Brardi, which bear a 

 superficial resemblance to that shown in fig. A, the parichnos is 

 clearly shown. On the other hand, an impression of a partially 

 decorticated Lepidodendroid stem need not necessarily show the 

 parichnos as a distinct feature : owing to its close association 

 with the leaf-trace in the outer cortex, before its separation in 

 the form of two diverging arms, it would not appear as a 

 distinct gap apart from that representing the leaf-bundle. 

 Thfe absence of the parichnos may be regarded as a point in 

 favour of the view that the impression is that of a partially 

 decorticated stem. Similarly, the absence of any demarcation 

 between a leaf-cushion and a true leaf-scar such as characterises 

 the stems of Lepidodendra and many Sigillariae is also favour- 

 able to the same interpretation. 



In 1872 Mr Carruthers^ described some fossils from Queens- 

 land, some of which appear to be identical with that shown in 

 fig. 187 under the name Lepidodendron nothum, Unger^, a 

 species founded on Upper Devonian specimens from Thuringia. 

 The Queensland plant is probably identical with Dawson's 

 Canadian species, Leptophloeum rhomhicum* . In 1874 M'Coy^ 

 instituted the name Lepidodendron australe for some Lower 

 Carboniferous specimens from Victoria, Australia: these are 

 in all probability identical with the Queensland fossils referred 

 by Carruthers to Unger's species, but as the identity of the 

 German and Australian plants is very doubtfuP it is better to 

 adopt M'Coy's specific designation. 



1 Seward (97^^) A. p. 326, PI. xxiii. 2 Carruthers (722). 



' Unger and Eiohter (56). 



■* Dawson (71) A. PI. viii. See also Smith and White (05). 



" M'Coy (74). See also Feistmantel (90) A. « Kidston (86) A. p. 231. 



