CYCADOFILICALES 25 



is now thought by Kidston (64) to belong most probably to the 

 Cycadofilicales. 



From the above statement it is evident that all of the so-called 

 "fern fronds" of the Paleozoic may well be "under suspicion." At 

 the same time, the actual proof of their connection with Cycadofili- 

 cales applies to so few species that it is very unsafe to assume that 

 there is no residuum of ferns among them. 



2. The spore-producing members 



THE MICROSPORANGIUM 



The microsporangia of Cycadofilicales were naturally regarded 

 at first as the sporangia of ferns, and it was not until 1905 that a 

 definite connection with one of the Cycadofilicales was announced 

 (54). The microsporangia were those of Lyginodendron Oldhamium, 

 thus completing in a remarkable way our knowledge of that form. 

 The original announcement (54) by Kidston was followed later 

 (64) by his full description and discussion. 



The stamen referred to proved to belong to Zeillee's form genus 

 Crossotheca, to which "fructifications" of a certain type have been 

 referred, and constituted a new form species (C. Honinghausii) . 

 The sporangium-bearing frond is dimorphic, but the fertile pinnules 

 are associated in the same frond with the sterile ones. To apply the 

 terms microsporophyll and stamen to this situation may be confusing 

 without an explanation. The whole frond is not strictly a micro- 

 sporophyll, and therefore not a stamen, but it well represents a frond 

 on its way to becoming a microsporophyll. In fact, only certain 

 pinnules bear microsporangia, and for convenience these fertile pin- 

 nules may be spoken of as microsporophylls or stamens. Each of 

 these primitive stamens (pinnules) has a very stout pedicel, which 

 is bent at its union with the oval blade, on the under surface of which 

 six or seven bilocular sporangia are developed (fig. 19). The spo- 

 rangia are fusiform and pointed (about 3 mm. long and i . 5 mm. in 

 maximum breadth), and apparently entirely free from one another. 

 The long axis of the sporangium is attached to the surface of the blade, 

 presumably in connection with a veinlet, and at the margin of the 

 blade the free tip is bent downward. When young, the free ends 

 bend inward, and the group of sporangia resembles a hemispherical 



