ZOOLOGY AND BOTANY, MICROSCOPY, EIC. 65 



CRYPTOGAMS. 



Pteridophyta. 



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



Phylogeny and Inter-relationships of Pteridophyta.*— I. Browne 

 has begun a series of articles intended to place before the student a 

 brief critical account of the principal views now held as to the phylogeny 

 and affinities of the Vascular Cryptogams. The inter-relationship of 

 the various types composing each phylum will be successively con- 

 sidered, and later on the affinities of the phyla to one another.' The 

 members of the fossil Sphenophyllales form the subject of discussion in 

 the first article, the Equisetales in the second, the Lycopodiales (Lepido- 

 dendraceas, Isoetaceaa, Selaginellacese, and Lycopodiaoeas) in the third 

 and fourth. At the end of each article is a bibliography of the papers 

 cited. 



Absence of Foliar Gaps in the Lycopsida.f — E. C. Jeffrey pub- 

 lished six years ago an account of his studies on the stem of the 

 Pteridophytes and Gymnosperms, and expressed the view that there are 

 two types of tubular central cylinder, namely, that in which only 

 ramular gaps are present, and that in whicli both ramular and foliar 

 gaps occur. Further, he stated that the Yasculares are divided into two 

 great primitive stocks : (1) the Lycopsida, which are cladosiphonic and 

 palingenetically microphyllous ; and (2) the Pteropsida, which are 

 phyllosiphonic and palingenetically megaphyllous. The Lycopsida in- 

 clude the Lycopodiales and Equisetales. The Pteropsida include the 

 Filicales, Gynmospermge, and Angiospermae. These two great stocks 

 appear to have been separate back to the beginning of the period when 

 the pala?ontological record begins. To this hypothesis various objec- 

 tions have been raised during the interval that has elapsed, but they 

 give the author no reason for modifying his standpoint in any essential 

 feature. In the present paper he shows that some of the objections to 

 the Lycopsida arose from misapprehension, etc. After replying to his 

 critics, he sums up as follows : — (1) True foliar gaps occur immediately 

 above their corresponding leaf-traces, and are not lateral to the leaf- 

 traces ; (2) true foliar gaps are absent in Phyttoglossum ; (3) they are 

 likewise absent in Tmesipteris ; (4) they are absent in the Lepido- 

 dendrere and the Sigillarige ; (5) they are unquestionably absent in the 

 cone axis of Equisetum, and on the basis of comparative anatomy are 

 absent also in the vegetative stem : similar statements apply to the 

 reproductive and vegetative axes of Catamites ; Archeocalamites has no 

 foliar naps in its vegetative stem ; (6) the Lycopsida, as defined by the 

 author, are clearly marked off from other plants by a palingenetically 

 niicrophvllous habit, the absence of foliar gaps in the tubular stele, and 

 by the possession of sporophylls with adaxial sporangia. They con- 

 stitute a great natural phylum. It should be added that in Phytto- 

 glossum and Tmesipteris perforations in the tubular stele sometimes 



* New Phytolog., vii. (1908) pp. 93-113, rO-66, 181-97. 

 t Bot. Gaz, xlvi. (1908) pp. 241-£8 (2 p'a ). 



Feb. 17th, 1909 F 



