Xl] SPHENOPHYLLOSTACHYS. 405 



may we regard each sporangiophore as a modified leaf, which 

 has become coherent with the whorls of sterile leaves ? Or is 

 a sporangiophore merely a stalk of a sporangium ; or a ventral 

 lobe of a leaf, of which the sterile bracts represent the dorsal 

 lobes? Although it is impossible without the evidence of 

 development to decide with certainty between these alter- 

 natives, it would seem most probable that a sporangiophore 

 may be looked upon as a ventral lobe of a leaf, the sterile lobes 

 forming the bracts or members of the sterile whorls of the 

 cone. This question is discussed by Zeiller^ and Williamson 

 and Scott-, also more recently by Scott^ in his memoir on 

 Gheirostrohus. 



Sphenophyllostachys Romei^i (Solms-Laubach)*. 

 Fig. 107, C and D. 



In another type of Sphenophyllum strobilus, recently 

 described by Solms-Laubach, the incurved end of each sporang- 

 iophore bore two sporangia. In most respects this species, 

 which has not been found in connection with a vegetative 

 shoot, agrees with Sphenophyllostachys Dawsoni. 



In fig. 107, C, which is copied from one of Solms-Laubach's 

 drawings^ we have an oblique transverse section of part of a 

 strobilus, including portions of two series of sporangia borne on 

 one verticil of bracts, and at the right-hand edge the section 

 has passed through the sporangia belonging to another whorl 

 of bracts. There were probably three concentric series of 

 sporangia attached to each verticil of bracts, as in the case of 

 fig. 108. The unshaded area, 6 (fig. 1 07, C), represents the bracts 

 of two successive sterile whorls in transverse section. The shaded 

 areas are the sporangia, with their sporangiophores, 8. The 

 relative position of the sporangia and sporangiophores suggests 

 that each pedicil bore two sporangia at its tip, instead of one, 

 as in the strobilus of Sphenophyllum cunei/olium (Stemb.). 



1 Zeiller (93), p. 37. ' Williamson and Soott (94), t- 'M'* 



3 Scott (97), p. 24. * Solma-Laubach («r>*). 



» Ibid. Pi. X. fig. «. 



