XXIX] LYGINOPTERIDEAE 51 



specimen (fig. 408, E, F) has confirmed the original description 1 . 

 The stellate lobes are now regarded as portions of a cupular 

 investment of a seed similar to Lagenostoma Lomaxi, the female 

 reproductive apparatus of Lyginopteris oldhamia. The axes of 

 the fertile pinnae bear small thorn-like emergences probably 

 identical with those on the cupule of Lagenostoma and on the 

 petioles of Lyginopteris oldhamia. It was stated in vol. n that 

 the fronds known as Sphenopteris Linkii (Goepp.) represent, 

 with other closely allied forms, leaves belonging to Heterangium 

 stems. This statement was based on a misconception : the rachis 

 of Sphenopteris Linkii, as I have satisfied myself by an examination 

 of impressions shown to me by Dr Kidston, exhibits the reticulate 

 pattern characteristic of Lyginopteris and not the transverse ribs 

 characteristic of Heterangium. 



It is not an easy task even for those most familiar with 

 Carboniferous fronds to distinguish clearly between species 

 agreeing generally with Sphenopteris Hoeninghausi, a species 

 regarded by some authors as the type of a group of very similar 

 and closely allied forms all of which were probably borne on 

 stems referable to the genus Lyginopteris. The species Lyginop- 

 teris oldhamia as generally understood probably includes more 

 than one specific type, and it is safe to assert that in the Carboni- 

 ferous period Lyginopteris was represented by several forms 

 characterised by highly compound fronds with forked rachises 

 like Sphenopteris Linkii, S. Hoeninghausi, and others. The 

 features characteristic of fronds included in the Sphenopteris 

 Hoeninghausi group have recently been described by Gothan 2 . 

 Stur's generic name Calymmatotheca originally applied to the 

 species C. Stangeri was applied to Sphenopteris Hoeninghausi by 

 Zeiller, and although the fronds of the latter type have not been 

 found with fertile appendages of the Calymmatotheca type there 

 can be no doubt as to the generic identity of these, barely distin- 

 guishable, species both of which belong to stems of Lyginopteris. 

 Prof. Johnson 3 has recently described some impressions from the 

 Coal Measures of Ireland, which he refers to S. Hoeninghausi, 

 bearing stellate groups of lobes like those of Calymmatotheca, and 

 in one case he describes a seed in the middle of the carbonised 



1 Oliver (05) fig. 6. 2 Gothan (13) p. 40. 3 Johnson (11). 



42 



