260 LYCOPODIALES [CH. 



the leaf-scars of the smaller forms of Bothrodendron. The 

 specimens from the Russian mines were first figured by 

 Trautschold and Auerbach^ as Lepidodendron tenerrimum and 

 afterwards referred by Zeiller to Bothrodendron punctatum^. 

 Nathorst', however, states that an examination of the Russian 

 material leads him to retain the name originally proposed ; he 

 records the same type from Upper Devonian rocks of Spitz- 

 bergen. The chief interest of these Russian specimens is their 

 manner of preservation, which Renault has described as the 

 result of bacterial action ; he claims to have recognised the 

 actual bacteria associated with the cuticular membranes ^ 



Anatomy of vegetative shoots of Bothrodendron. 



In 1889 Williamson^ described several specimens of petrified 

 shoots from the Coal-Measures of Halifax which he named 

 Lepidodendron mundum : these are now known to be branches 

 of a Bothrodendron. The discovery was made by Mr Lomax* 

 who found specimens showing the external characters of Both- 

 rodendron and the anatomical characters of Lepidodendron 

 mundum. In some of the smaller twigs, the stele consists of a 

 solid core of xylem with external protoxylem ; but in the 

 majority of specimens the centre of the xylem is replaced by 

 parenchymatous tissue, either as a small axial strand or, as in 

 the specimen shown in fig. 215, D, a wide pith, the elements of 

 which are arranged in regular vertical series. A diagrammatic 

 section of a small axis is represented in fig. 215, A : this branch, 

 2 mm. in diameter, is composed of a broad outer cortex con- 

 sisting exclusively of primary tissue the outer cells of which 

 are smaller and have thicker walls than the more internal 

 elements. The leaf-traces. It, are accompanied by a strand of 

 delicate tissue, the parichnos. The stele is almost solid; the 

 tissues in contact with the xylem have not been preserved but 

 the inner cortex is represented by a few layers of small paren- 



1 Trautschold and Auerbaoh (60) PI. iii. 



2 Zeiller (82) A. ; (86). a Nathorst (94) A. Pis. x. xi. 



* Volume I. p. 134. » Williamson (89) A. p. 197. 



* I am indebted to Mr Lomax for photographs of his specimens. For former 

 references to Mr Lomax's discovery, see Kidston (05); Weiss, F. E. (08)- Scott 

 D. H. (08) p. 200. ' 



