520 Scientific Proceedings^ Royal Dublin Society. 



under or abaxial side, and a prouounced ridge on its upper side, probably 

 fitting into the groove on the under side of the sporophyll immediately above 

 it in the cone. On either side of this ridge tliere is a line or slight groove 

 (parichnos-continuatiou ?). Deprived of its fertile proximal end the sporophyll 

 appears similar to an ordinary foliage leaf. It is on the upper or adaxial side 

 of the megasporophyll that the megaspores are borne. They are 1 mm. in 

 diameter and rounded or, as sometimes seen, pyriform bodies. Schimper's 

 figure of the sporophyll of L. Baili/ana shows numerous megaspores each with 

 a triradiate mark, indicative of an origin by division of the megaspore mother- 

 cell into four si^ores. As the drawing was made ad naturam, and as it is stated 

 that all the megaspores showed the mark, I must content myself by stating 

 that, though one may safely assume that tetrad divisions took place, 

 I have found nothing comparable to Schimper's figure in the very many 

 sporophylls I have examined. 



Occasionally the spores have appeared arranged as if with a common 

 origin. Thej^ are found more or less in two rows on each side of the midrib, 

 from ten to twenty in number in each sporophyll. Detached ones are not 

 uncommon in the rock, as well as rounded depressions in the sporophyll, 

 showing their seat of origin. They all show a thick carbonaceous coat — the 

 spore-wall — occasionally seen broken through and revealing an enclosed 

 cavity. 



The presence of so many megaspores in the one megasporangium in 

 B. kiltorkeiise is interesting, and adds to the likeness first noted by Schimper 

 of the Kiltorcan sporophyll to that of Isoetes. An additional feature deserves 

 mention. I have frequently noticed at the point of union of the fertile base 

 with the sterile lamina on the upper side a distinct carbonaceous plate, semi- 

 lunar in shape. In some cases the plate is absent, but its extent is indicated 

 by an impression limited by a curved ridge ou the sterile part of the sporophyll, 

 above the spore-bearing base. I take this to be the ligule coming, as in Isoetes, 

 between the sporangium and the sterile distal part of the sporophyll. I have 

 attempted in the accompanying figure (text-figure 5, p. 621) a restoration of a 

 female sporopliyll (cp. Plate XLI, figs. 6, 7, 8). I had decided to omit this 

 suggestion of the possible presence of a ligule when I saw tliat Heer states 

 that every sporophyll of B. kiltorkeiise appears to have possessed an oval 

 papilla or flap lying between the fertile base and the sterile bristle-like 

 appendage (op. cit., Tf. xi). 



I give a figure (text-figure 6) of tlie appearance presented by one mega- 

 spore, and feel emboldened to do so owing to the discovery by K. C. McLean 

 (27) of the presence in the megaspore of B. mundum of a prothallus projecting 

 in a manner not unlike that in the germinating megaspore of a Pilularia or a 



