In 1905 Kidston[131] announced the discovery of microsporangia on fronds of _Lyginopteris_: he described specimens from the Coal Measures of Dudley identified by him with _Sphenopteris Hoeninghausi_ showing sterile and fertile pinnae in organic connexion. The fertile pinnules (fig. 407, B) are slightly expanded distally into an oval limb about 2 mm. long bearing 6 to 7 bilocular fusiform microsporangia 3 mm. long and 1·5 mm. broad: in the immature condition the sorus is hemispherical, the summit being formed of the incurved apices of the sporangia. At maturity the sporangia spread out, the sorus assuming the form of an epaulet. Fig. 408, H, shows a sorus in transverse section and in fig. 408, G, the limb and two pendulous sporangia are shown. The microspores, 50–70 µ in diameter, are studded with numerous blunt spines and each spore shows a triradiate ridge. The section reproduced in fig. 407, A, from the Coal Measures of Oldham is probably a bilocular sporangium of the same type as those described by Kidston from Dudley. Dr Kidston[132] describes a second type of microsporangial sorus as _Crossotheca Hughesiana_ which agrees closely with _C. Hoeninghausi_, but the fertile segments are not associated with any sterile pinnae. The generic name _Crossotheca_, founded by Zeiller[133] in 1883, was substituted for _Sphenopteris_ on the ground that Brongniart’s species _S. Hoeninghausi_ is shown to possess sporangia of the _Crossotheca_ type. If Kidston’s specific determination is correct, his discovery demonstrates that _Lyginopteris_ fronds bore microsporangia having the characters of _Crossotheca_, a type characteristic of several Carboniferous species belonging both to the form-genera _Sphenopteris_ and _Pecopteris_. Reference has already been made to the difficulty of distinguishing between impressions of fronds of the _Sphenopteris_ _Hoeninghausi_ group, a difficulty that is illustrated by Dr Gothan’s statement[134] that the Dudley specimens of _Crossotheca_ are not identical in the character of the sterile pinnules with _Sphenopteris Hoeninghausi_. An examination of Dr Kidston’s specimens led me to agree with his determination; but, it may be asked, have we any evidence of the association with _Lyginopteris_ fronds of sporangia other than those of the _Crossotheca_ type? Prof. Chodat[135] believes that certain petrified fragments of pinnules occasionally met with in the calcareous nodules bearing sessile and apparently annulate sporangia belong to _Lyginopteris_ fronds. These sporangia appear to be identical with those named by Scott _Pteridotheca Butterworthi_[136] and regarded by him as filicean sporangia that cannot be referred to any known Carboniferous genus. The piece of lamina bearing an empty sporangium, which may or may not have possessed an annulus, reproduced in fig. 407, C, occurs in association with the larger specimen shown in fig. 404, B, and it would seem not unreasonable to regard both as parts of the same frond, namely a