Geology and Natural History. 473 



II. Geology and Natural History. 



1. Recent Contributions on Cycadophytans ; by G. R. Wie- 

 lanc. — After the article on the Williamsonian tribe (pp. 433-466 

 of this Journal) was in type, two highly important contributions 

 on the subject by Nathorst and Schuster came to hand and ai"e 

 hei'e added to the literature cited with comments: — 



(29) 1911. — Nathorst, A. G. Paleobotanisehe Mitteilungen 10. Ueber die 



Gattung Cycadocarpidium Nathorst nebst einige BemerkungeE 

 ilber Podozamit.es. Kungl. Svenska Vet.-Ak. Hand]., vol. xlvi, 

 No. 8, pp. 11 and pi. 



In this brief paper Professor Nathorst again displays his gift 

 for making scanty plant remains reveal the presence of little sus- 

 pected ancient groups. As it now turns out, Cycadocarpidium 

 (Nathorst, 1886) is a loosely compacted strobilus of very leafy 

 two-seeded megasporophylls, and is so intimately associated with, 

 and so like the leaves of Podozamites as to leave no doubt but 

 that the fossils referred to these genera are leaf and fruit of the 

 same plant. 



On the basis of the strobilus alone, a primitive leafy cycadace- 

 ous type (such as is readily pictured from abnormal cones of 

 Encephalartos described by Thiselton-Dyer, or those of Zamia 

 brought to notice by Wieland) would at once be inferred. But 

 it is also shown by Nathorst that the leaf-laminae of Podozamites 

 are not all laterally borne pinnules of a once pinnate frond as 

 hitherto considered, but are in part the spirally borne leaves of 

 small scale-covered stems of presumably limited growth and dis- 

 tinctly coniferous habit ; from which it is obvious enough that 

 Podozamites is perhaps the first form ever determined from that 

 unknown borderland between cycads and conifers. 



Thus the correctness of my rather free — even if qualified — 

 reference of Podozamites to the Williamsonian alliance is brought 

 under suspicion. Though it must be remembered that the pres- 

 ence of the small branches accompanying Cycadocarpidium (or 

 better Podostrobus) does not take away from the possibility that 

 the as yet wholly unknown microsporophylls were of more or less 

 distinctly leafy to Williamsonian type. 



(30) 1911.— Schuster, Julius. Weltrichia und die Bennettitales. Kungl. 



Svensk. Vet.-Ak. Handl., vol. xlvi, No. 11, pp. 57 and 7 pis. 



It is always interesting to note how repeated consideration of 

 problematical fossil structures may serve to hasten the day of 

 their elucidation. Nor can a better instance be cited than the 

 curious disk Weltrichia mirabilis (Fr. Braun, 1848). In the 

 Plantes Jurassiques Saporta refignred this fossil and for the first 

 time divined its affinity to Williamsonia, although utterly mis- 

 apprehending its true function in supposing it to be a funneli- 

 form termination of the strobilar axis, of which there is after all 

 no definitely known instance in any Williamsonian form. 



