1907] CURRENT LITERATURE 221 
Under the Pteropsida are grouped the classes Filicales, Pteridospermeae, and 
ymnospermeae, the two latter being regarded as of coordinate importance and 
constituting the Paleozoic Spermophyta. The author in his discussion of the 
cales makes a strong stand against the tendency to include all paleozoic fili- 
coid plants in the Pteridospermae. He points out that there is clear evidence 
that the Botryopterideae of RENAULT were true ferns. This is likewise in all 
probability true of other apparent filicinean remains, of unresolved affinity, 
characterized by the presence of annulate sporangia, for which the author pro- 
poses the form-generic name Pieridotheca. There is further good evidence in 
fruiting fronds referred to Ptychocarpus, Asterotheca, etc., with synangial spo- 
rangia resembling those of existing Marattiaceae, as well as in stems presenting 
the anatomical structure of Psaronius, for the existence of ferns like the Marat- 
tiaceae in paleozoic times. 
The paleozoic seed-plants are included under two coordinate classes: the 
Pteridosperm(e)ae and Gymnosperm(e)ae, which are spelled with an unusual 
and perhaps superfluous e. The description of the Pteridospermae (Cycad- 
ofilices of Potonré) contains little which is not to be found in the author’s lecture 
before the Vienna Congress. He states very clearly however his reasons for 
regarding the Pteridospermae as a group coordinate with the remaining gymno- 
sperms as at present recognized: (1) the mega- and microsporangiate sporo- 
phylls were little modified from ordinary vegetative fronds; (2) the anatomical 
structure was more clearly fern-like than that found in any other gymnosperms. 
It may well be objected, however, that the Pteridospermae were essentially gymno- 
sperms, that the Cycadophyta, taken as a group, present equally fern-like mega- 
and microsporophylls, and that the anatomical peculiarities of the Pterido- 
spermae can nearly all be duplicated in the lower Gymnospermae. Whether or 
not the Pteridospermae stand as a distinct class coordinate with the remaining 
Gymnospermae, there can be no question that their discovery constitutes the 
principal advance in many years in our knowledge of the Spermaphyta. | 
botanists must be grateful to the author for his lucid and interesting account of 
paleozoic plants, which he has done so much to restore and rescue from oblivion. 
In looking over these pages, one is tempted to call the article an original compila- 
tion, so large and important, albeit not in any way disproportionate, a part, do 
the author’s own investigations make of the whole.—E. C. JEFFREY. 
Cytological studies on the Cyanophyceae.—Two contributions’ *® on the 
cytology of the Cyanophyceae have recently appeared, which add a few new 
features to an already much confused subject. GARDNER regards as the chief 
trouble which has obscured the truth for former investigators their ‘failure to 
discover a method which would clearly, definitely, and unmistakably differen- 
15 GARDNER, N. L., oo studies in Cyanophyceae. Univ. Calif. Pub. Bot. 
22237-0906. pls. 21-26. 
6 GUILLIERMOND, A., Contribution & — faites des Cyanophycées. Rev. 
Gén. Bot. 18: 392-408, pa pls. 9-13. 
