CARBONIFEROUS LYCOPODS AND SPHENOPHYLLS. 129 



nodes are not shortened, and the bracts not more reduced in the 

 limb than is seen in the segmented leaves of the ordinary foliage 

 branches. Nor do they seem to have a " knee " where the distal 

 portion usually uprises, but, as far as one can judge, the bracts 

 stood out from the axis like the ordinary foliage leaves. They 

 are, however, united at the base into a narrow collar or sheath 

 which surrounds the axis. 



The sporangia are usually more or less displaced, and it is very 

 difficult to ascertain their true position on the bracts, or how 

 many circles they formed. I am 

 inclined to think they have been 

 placed in two concentric circles, 

 though on the specimen from 

 which the figure was taken only 

 one group was present. 



The pyriform sporangia are Fi g- 25. — Sphenophyllum. majus, 



united by their bases into groups Bronn ' . Bract sh °wing four 



£ n , t_ . . , , t_ sporangia — sessile and united to 



or tour: on this point there can- , * . .,. , 



1 each other by their bases, 

 not possibly be any doubt; and 



that this is so is shown by the fact that when they are removed 



from the bracts they generally occur in the shale, still united in 



groups of four. 1 I can find no trace of a sporangiophore or pedicel, 



and if such a structure is present it must be reduced to a very 



short point where the four sporangia unite. 



Several authors have proposed the union of Trizygia, Royle. 2 

 The fructification of Trizygia appears to be unknown, and it is 

 therefore only the foliage branches that are available for com- 

 parison. In Trizygia each node bears a whorl of six cuneate 

 leaves, but the two lateral pairs are larger than the anterior 

 pair. On the inequality of the size of the leaves in Trizygia lies 

 the chief difference between it and S-phenophyllum. 



The discovery of some specimens by M. de Bosniaski in the 

 Palaeozoic rocks of Monte-Pisano, apparently belonging to 

 Trizygia, led M. Zeiller to communicate an interesting paper, 



1 Sometimes six sporangia appear to form a group. 



2 Royle, " Illustrations of the Botany and other Branches of the Natural 

 History of the Himalayan Mountains and of the Flora of Cashmere," 

 p. 431. 1839. 



