522 Scientific Proceedings^ Royal Dublin Society. 



Hitlierto one kind of sporophyll only — tlie female one — lias been identified 

 and described. There is no difficulty in recognizing, especially witii a lens, 

 the ripe megasporophyll, as the megaspores stand out well (Plate XLT, fig. 7). 

 Some of the sporophylls, however, both in the cone and when isolated, 

 show a smooth surface in the thick basal part. They are not megasporophylls 

 which have shed their megaspores, as these leave a pit behind. They may be 

 immature megasporophylls or young male or microsporophylls. There are, 

 in addition, sporophylls in which the basal part shows a wrinkled or rugose 

 surface (Plate XLI, fig. 6), whether natural or due to shrinkage I cannot say. 

 Such sporophylls with puckered base suggested themselves as the missing 

 microsporophylls. I played on some of them with the blowpipe, saw them 



.4- 



Fia. 7. — Miorophotograpli of microspore of Bothrodendron Inltorlcense. Magnified. Microspore 

 spherical, wall finely punctate, 0-05 mm. in diameter. (Fielfl disfigured by particles of rock.) 



glow as the carbonaceous matter was burnt, on cooling removed the remainder, 

 crushed it in an agate mortar, and treated it with Schulze's macerating 

 mixture, followed by ammonia, to remove any ulmic acid present, and then, 

 after heating, examined the resulting material microscopically. Many 

 rounded bodies, some with a triradiate mark, were seen ; and I feel justified 

 in concluding that they are the microspores obtained from the micro- 

 sporangium. If my conclusion is justified, the apical strobilus of B. kiUorkense 

 may be described as heterosporous, consisting of an axis carrying whorls of 

 megasporophylls and of microsporopliylls. I leave the question of the distri- 

 bution of the sporophylls in the cone an open one at present, being content to 

 record the general agreement, in the possession of a heterosporous cone, of 

 B. Mltorkeme with B. mimdimi and certain other Lepidophytes. Schimper 

 suggested the desirability of a search for the male spores in the Irish 

 material, and Heer speaks of minute black granules he saw in Bear Island 

 material as, in all likelihood, microspores. B. kiUorkense is thus the earliest 

 illustration of heterospory yet known. 



Bislrihution. 

 In his " Fossil Botany " (vol. ii, p. 257) Seward gives a generalized account 

 of the distribution in time and space of Bothrodendron kiUorkense and of species 

 more or less identical with it. It seems clear from the records that the 



