182 LYCOPODIALES [CH. 



compression the cylinder of bark may assume the appearance of 

 a flattened stem covered with leaf-cushions. A specimen pre- 

 served in this way was described by E. Weiss as a cone ofLomato- 

 phloios macrolepidotus Gold., and is quoted bySolms-Laubach and 

 other authors^ as an example of an unusually large Lepidostrobus. 

 An examination of the type-specimen in the Bergakademie of 

 Berlin convinced me that Weiss had mistaken the partially 

 destroyed leaf-cushions for sporophylls, and Stigmarian rootlets, 

 which had invaded the empty space, for sporangia". 



In external appearance some species of Lepidostrobus bear a 

 superficial resemblance to the cone of a Spruce Fir (Picea 

 excelsa), but the surface of a lycopodiaceous strobilus is usually 

 covered by the overlapping and upturned laminae which 

 terminate the more or less horizontal sporangium-bearing 

 portion of the sporophyll. 



Fig. 188 affords a good example of a long and narrow 

 Lepidostrobus. This specimen from the Middle Coal-Measures 

 of Lancashire has a length of 23 cm. ; like other Lepidostrobi 

 it is borne at the tip of a slender shoot. The fossil is suffi- 

 ciently well preserved to show the characteristic radially 

 elongated form of the large sporangia and the long and up- 

 turned distal portions of the sporophylls. 



We may briefly describe Lepidostrobus as follows : — Cylin- 

 drical strobili consisting of an axis containing a single cylindrical 

 stele which agrees generally with that of the vegetative 

 shoots of L. Harcourtii and other species. The amount of 

 parenchymatous pith varies in different forms ; in some the 

 primary xylem is almost solid. The middle cortical region, 

 which has usually been destroyed before fossilisation, possesses 

 the loose lacunar structure characteristic of this region in the 

 vegetative branches. The thicker walled outer cortex is con- 

 tinued at the periphery into crowded, usually spirally disposed 

 sporophylls, each of which consists of a more or less horizontal 

 pedicel, which may be characterised by a keel-like median 

 ridge on its lower surface, while to the central region of the 

 upper face is attached a large radially elongated sporangium. 

 One of the chief differences between a Lepidodendron cone 

 1 Bower (08) p. 305. a Seward (90) ; Potonie (932). 



