It is not uncommon to find _Lepidodendron_ preserved in the form of a shell of outer cortex, which has become separated along the phellogen from the rest of the stem; as the result of compression the cylinder of bark may assume the appearance of a flattened stem covered with leaf-cushions. A specimen preserved in this way was described by E. Weiss as a cone of _Lomatophloios macrolepidotus_ Gold., and is quoted by Solms-Laubach and other authors[408] 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[409]. 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 sufficiently well preserved to show the characteristic radially elongated form of the large sporangia and the long and upturned distal portions of the sporophylls. We may briefly describe _Lepidostrobus_ as follows:—Cylindrical 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 continued 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 and those of the recent genus _Lycopodium_ is the greater radial elongation of the sporangia in the former. Some species of _Lepidostrobus_ may have been homosporous; some are known to be heterosporous. In the latter the megasporangia borne on the lower sporophylls usually contain several megaspores as in _Isoetes_ (cf. fig. 133, E). Beyond the distal end of the sporangium the sporophyll becomes broader in a horizontal plane and is bent upwards as a lanceolate limb; it may also be prolonged a short distance downwards as a bluntly triangular expansion.