XXIX] LAGENOSTOMA 63 



are, however, indications that mucilage was poured out by the 

 rupture of the distended cells. Some microspores were found 

 in the pollen-chamber with an average size of 72 x 53 /j,; they 

 may be as much as 90 ju, long. None were observed with sperm- 

 like contents like those described by Dr Benson. Miss Prankerd 

 discusses the morphology of the integument in relation to that 

 of cycadean seeds and makes an instructive comparison between 

 the lagenostome (that is the modified nucellar apex) and such 

 fern sporangia as those of Angiopteris, Osmunda, and Schizaea, 

 but especially the sporangia of Senftenbergia^ with their multiseriate 

 annulus. 



An interesting feature is shown in the longitudinal section 

 reproduced in fig. 493, A (p. 311). The apex of the nucellar 

 cone appears to be composed of thick-walled, dark cells and it 

 is suggested that this may have served as a stopper blocking up 

 the circular orifice of the pollen-chamber (seen below the apex 

 between the nucellar cone and the thick surface-layer of the 

 nucellus) and serving as a protection to the embryo. A comparable 

 closing-up of the micropyle occurs in the seeds of Gnetum Gnemon^ 

 and in the beak of cycadean seeds. At the time of pollination, 

 when the pollen-chamber must have extended to the apex of 

 the lagenostome, the tip of the nucellar cone may have secreted 

 some sticky substance to which the microspores would adhere. 



Prof. Lignier^ has recently described some large megasporangia 

 from the Westphalian Coalfield of Ostrau in Austrian Silesia 

 which he made the type of a new genus Mittagia, after Herr 

 Mittag, Director of Mines. Two sporangia, between 2 and 3 mm. 

 in diameter, were foimd in close association as though belonging 

 to a single sorus; one was empty and the other contained four 

 megaspores. The structure of the thick wall of the sporangia 

 is very similar to that of the testa of Lagenostoma Lomaxi, but 

 it apparently split into two valves. Lignier refers the new type, 

 Mittagia seminiformis, to some unknown Palaeozoic group of 

 heterosporous Filicineae, possibly the ancestral stock of the 

 Pteridosperms, and he thinks it probable that the sporangia 

 resembled seeds in their facilities for dispersal. In the structure 



1 Vol. n. p. 364, fig. 270. ^ Berridge (11). 



' Lignier (IS^). 



