CYCADOFILICALES 



29 



occur structures, of the Calymmaiotheca type. It must be confessed 

 that while the Crossotheca or "epaulet" type of stamen is distinct 



22 -23 



Figs. 22, 23. — Crossotheca Honinghausii: fig. 22, diagrammatic longitudinal 

 section of stamen; fig. 23, diagrammatic transverse section of stamen; /, limb; s, spo- 

 rangia; m, rock matrix. — After Kidston (64). 



enough, the so-called Calymmaiotheca or "cupule" type is in con- 

 fusion, and so far as it represents microsporangiate structures at all, 

 they may be referred ultimately to Crossotheca or to 

 ordinary marattiaceous synangia, like those of 

 Kaulfussia. 



Although actual organic connection of stamens 

 with plants known to be seed-bearing has been 

 discovered as yet in only two or three forms, it 

 is evident that a much wider range of forms is 

 indicated. All structures of the Crossotheca type 

 may fairly be considered probable stamens of 

 Cycadofilicales, and some of the Calymmatotheca 

 structures, so far as they are distinct from large 

 marattiaceous synangia, are doubtless such also. 

 It must be noted, however, that the frond genera 

 and the sporangium genera cross one another's 

 boundaries. For example, Crossotheca occurs on 

 both Sphenopteris and Pecopteris; while Calym^ 

 matotheca (or its equivalents) occurs on Neurop- 

 teris, Sphenopteris, and probably Aneimites. The dimorphic charac- 

 ter of the fronds is quite marked in all these cases, and it sug- 

 gests the question whether other dimorphic fronds, bearing sporangia 

 of a different type, may not belong to Cycadofilicales. Furthermore, 

 the great frond genus Pecopteris, one of whose species, at least, is 

 known to belong to the Cycadofilicales, possesses all the types of spo- 



FiG. 24. — Codo- 

 notheca; X2. — After 

 Sellaeds (40). 



