518 Scientific Proceedings, Roijal Dublin Society. 



Stigmaria Appendages. 



As the illustrations show (Plate XL, figs. 4 and 5), the Stigmaria 

 appendages in Bothrodendron are well developed. In the one figured they 

 are, as far as traceable, 24 cm. long and as much as 2 cm. wide. Eunning 

 through the appendage is a single vascular strand. Unlike Stigmarian 

 appendages generally, wliich, according to Potonie, very rarely branch, these 

 appendages branch several times, but not apparently dichotomously, and they 

 become more root-like in tlieir finer ramifications. Tlie impressions show 

 the continuity of the axial strands in parent and lateral appendages. The 

 appearance of the appendage suggests a bulky soft tissue surrounding an 

 axial strand, indicative of an organ growing in a swamp. It is of interest 

 to note that the appendage branches show a constricted base of attachment. 



Though " Stigmaria " is rare in the Devonian rocks, it is described as one 

 of the commonest fossils in the Carboniferous epoch. Its anatomical structure 

 and that of its appendages have been fully worked out. The text-books by 

 Scott and by Seward give fully illustrated accounts. The " Stigmaria " 

 axis, with its bifurcation, is regarded as more comparable to the rhizophore 

 of a Selagiuella than to a rhizome. The appendages, though formed, it 

 appears, exogenously, are roots functionally and structurall3^ The monarcli 

 vascular strand is normally central, but becomes excentric owing to the 

 breaking down of tlie loose lacunar tissue forming the greater part of the 

 bulk of the appendage. 



Strobilus. 



The little already known of the cones or strobili of different species of 

 Bothrodendron reveals considerable variety of structure and arrangement, 

 with heterospory, so far as the cones are known, as a character in common. 



B. niicndtim as described by Watson shows a diminutive cone. The fertile 

 axis bears a small number of spirally arranged sporophylls, not radially 

 elongated. Each sporophyll carries on its upper side either a spherical 

 megasporangium or a microsporangium, and inserted above this a short 

 evascular ligule. The cone is astonishingly like that of Selaginella. 

 B. minutifoUum, on the other hand, possesses a long, narrow, cylindrical, 

 terminal cone with radially elongated sporangia, described by Zeiller as 

 Lepidostrobus Olryi. The statement that B. punctatum possesses short, blunt, 

 lateral cones terminating deciduous shoots arranged in two opposite rows 

 on the older branches, as figured by Kidston in his restoration of the 

 species, needs confirmation in view of Eeuier's discoveries that the two rows 

 of Ulodendroid scars are vegetative and not reproductive in origin. 



