The account of the Sphenophyllales given in the first volume[2] of this work must be extended and somewhat modified in the light of recent work on the fertile shoots of _Sphenophyllum_. _Sphenophyllostachys Dawsoni_ (Will.) was described as consisting of an axis bearing superposed whorls of bracts connate at the base in the form of a shallow funnel-shaped collar giving off from the upper surface and close to the axis of the cone two concentric series of sporangiophores. Occasionally there are three series, as represented in fig. 112. In another type of strobilus, _Sphenophyllostachys Römeri_[3] each sporangiophore terminates in two pendulous sporangia (fig. 113, A; see also fig. 107, C, vol. I.). It has already been pointed out that the common occurrence of detached strobili necessitates their description under distinct specific names; it is only by a rare accident that we can assign fossil cones to their vegetative shoots. There are, however, reasons for believing that _Sphenophyllostachys Dawsoni_ is the strobilus of the plant originally described by Sternberg[4] from impressions of foliage-shoots as _Rotularia cuneifolia_. Another difficulty presented by petrified material is that of determining, with certainty, whether two imperfect specimens, differing from one another in features which do not appear to be of sufficient importance to warrant specific separation, are forms of one species or portions of specifically distinct cones. It has been pointed out by Scott[5] that the strobilus known as _Sphenophyllostachys Dawsoni_ probably includes two distinct species, one being the cone of _Sphenophyllum cuneifolium_ Sternb., and the other the cone of _S. myriophyllum_ Crép[6]. The stem of _S. myriophyllum_ agrees anatomically with the type known as _Sphenophyllum plurifoliatum_ Will. and Scott[7]. [Illustration: FIG. 112. Sketch of a radial longitudinal section of _Sphenophyllostachys_. There are usually two concentric series of sporangia on the sporophylls, not three as shown in the figure. The upper figure (after Zeiller) shows the linear bracts in surface-view.]