Palaeontologie. 559 



The paper concludes vvith an account of the Geological 

 Distribution of the Slgillarlae, especially of the species in which 

 the structiire is known. He ünds that a continuous ring of 

 primary xylem is the older type of Slglllarlan stem structure, 

 and that the circle of isolated Strands, which form the primary 

 xylem of the Clathrarlan Sigillariae of the higher Geological 

 horizons, has originated by the Splitting iip of the continuous 

 ring type of primary wood. Arber (Cambridge). 



Scott. D. H., What were the Carboniferous Ferns? 

 (Presid. Address, Journ. Roy. Microsc. Soc. Vol. for 1905. 

 p. 137—149. Pis. I.— III. and Text figs. 32—33. 1905.) 



Of all the groups contributing to the Carboniferous Flora, 

 the Ferns, commonly so-called, are by far the most important 

 in number of species, amounting to about half of total known 

 Flora. If then the „Ferns" of the Carboniferous were really 

 Ferns, in the true sense of the word, their numbers would 

 suffice to establish the truth of Brongniart's description of 

 the Palaeozoic epoch as the „Reign of the Acrogens". In the 

 present paper, the real nature of Carboniferous fossil plants, 

 commonly described as ferns, is di&cussed. After contrasting 

 the habit of some of the best known genera, the author points 

 out that in only a few cases, especially belonging to the large 

 genera Pecopteris and Sphenopterls, has any trace of a true 

 Fern-fructification been found. Typical instances are figured 

 and described, both of fructifications preserved as impressions 

 and also as petrifications. It is stated, however, that out of 

 some 147 British species of fern-like fronds, there are only 27 

 which we can attribute with any certainty to true Ferns, on 

 the ground of fructification. Of the remaining 120, 75 are still 

 altogether doubtful, while in 45 the probability is all on the 

 side of an affinity with seed-bearing plants. 



The author next proceeds to a discussion of the investi- 

 gations which have afforded indications of the real nature of 

 these quasi-ferns; more especially the discovery of the seed of 

 Lyginodendron, and other recent researches on the seed-bearing 

 habit of these plants. He concludes that among the Carboni- 

 ferous plants commonly described as Ferns, a certain number, 

 but, as appears probable, only a minority, were really of that 

 nature, as is shown by their Filicinean fructification. Among 

 these true Ferns, the Marattiaceae were largely represented; 

 other families also existed, though probably not identical with 

 any of the groups now living. A large number of the so- 

 called Ferns, probahly the majority, were not, properly spea- 

 king, Ferns at all, but seed-bearing plants, most nearly allied 

 to such recent Gymnosperms as the Cycads, while at the same 

 time retaining some of the characters of their cryptogamic allies. 



Of all living seed-plants, the Cycads stand nearest the Ferns 

 among Cryptogams. The Pteridosperms of the Palaeozoic era, 



