92 SUMMARY OF CURRENT RESEARCHES RELATING TO 



CRYPTOGAMS. 



Pteridophyta. 

 (By A. CtKPP, M.A. F.L.S.) 



Phylogeny of the Filicales.* — F. 0. Bower, continuing his studies 

 in the phylogeny of the Filicales. publishes an account of Gheiroplpuria 

 bmiapis Presl, and certain otlier related ferns. In summing up his 

 results he says : — 1. Cheirophuria bini.'ipis is the only known species of 

 a substantive genus. 2. It shows an uncommon mixture of primitive 

 and advanced characters, by which it takes a place phyletically as a 

 synthetic form. 3. Its characters, external and internal, connect it 

 downwards most clearly with DipUris ; and upwards — that is, in the 

 direction of more advanced specialization — with Platyceriwn. 4. Its 

 simple hairy investment, protostelic axis, undivided leaf-trace, and its 

 frequently bifurcate form of leaf are relatively primitive characters. 

 5. Its reticulate venation and its " Acrostichoid " and " mixed " sorus 

 are characters of relative advance. G. The occasional extension of the 

 receptacular vascular supply of the individual sorus beyond t!ie single 

 vascular areola gives the clue to tlie state of the sporophyll in Plalycerinm, 

 with its double vascular system in the fertile region. 7. Its' slightly 

 oblique annulus, four-rowed sporangial stalk, and alternate segmentation 

 of the primordiutn form a peculiar link with Dipteris, which is shared 

 also by Metaxya. 8. The mixed characters which this fern shows sup])ly 

 one of the clearest examples of non-parallelism in progression in the 

 several criteria used for comparison among ferns. 9. The outcome of 

 its comparative examination is to strengthen the relation of Dipferis 

 and Matonia to some Gleicheniaceous source. 10. It shows that 

 probal)ly Platycerium is also a Dipterid derivative, specialized for an 

 epiphytic habit. 11. Probably other Dipterid derivatives will also be 

 found on detailed study, in such forms as Lepfochilus, Neocheiropteris, 

 and some others. 12. Thus the representation of Matouioid-Dipteiid 

 derivatives among living ferns appears to l)e more extensive than had 

 ))een hitherto appreciated. 



Rachiopteris cylindrica.f — N. Bancroft publishes a contribution 

 to our knowledge of Rachiopteris cyUndrica Will., with the following 

 summary : — 1. The species is restricted to the Halifax Hard Bed of 

 Lower Coal Measure Age. 2. The stems and petioles may be referred 

 to two types, described respectively as a and [d. (i.) a stems have a 

 well-developed xylem strand tending to mesarch structure, with diiferen- 

 tiation of the central elements ; the inner and middle cortical areas 

 have fairly thick-walled cells, while the outer cortex is composed of a 

 few layers of thin-walled cells, suggestive of an assimilatory tissue. 

 a petioles also have well-developed xylem strands, frequently with 

 distinct diarch structure ; their cortex is like that of a stems, 

 (ii.) /? stems possess only a small mojiarch, centrarch xylem strand. 



* Ann. Bot., xxix. (1915) pp. 495-529 (2 pis. and figs.), 

 t Ann. Bot., xxix. (1915) pp. 531-65 (2 pis. and figs.). 



