228 BOTANICAL GAZETTE [SEPTEMBER 
the important facts well in view, however opinions may differ as to some of the 
conclusions. It is shown that the fern-like Cycadofilices, later called Pterido- 
sperms, were a dominant group of the Carboniferous; but that the evidence for 
the existence of ferns in the modern sense is at present very uncertain. For 
any Carboniferous fern-like plants that may prove to be true ferns the author 
suggests the name Primofilices, since to distinguish among them definite euspor- 
angiate and leptosporangiate habits is impossible. In fact, all the so-called 
“*fructifications” of Paleozoic ‘“‘marattiaceous ferns’? may prove to be the 
microsporangiate structures of Pteridosperms. Until this is determined, the 
existence of eusporangiate ferns in the Paleozoic as a dominant group must 
remain uncertain. This also means that the old question as to whether the 
eusporangiate or the leptosporangiate type of ferns is the more primitive has 
lost its apparently sure answer from history. In fact, while the author gets 
sure evidence of leptosporangiate ferns in the Permian, he does not find similar 
satisfactory evidence of eusporangiate ferns until the Tertiary; although in both 
cases he recognizes the possible Paleozoic occurrence. As to the water ferns, 
the evidence of their existence does not become clear until the Tertiary. The 
claims for them in the Paleozoic are so much in conflict with all morphological 
testimony that they have never seemed to be very serious. The general con- 
clusion in reference to the ferns seems to be that while Pteridosperms are @ 
dominant group in the Paleozoic; and the Cycadophyta are one of the dominating 
groups of the Mesozoic; there is no evidence at present of the dominance of ag 
fern group except that of the leptosporangiates in the Mesozoic and continuing 
into the present flora.—J. M. C. 
natans, and of Lewis" on R. crystallina. The spore mother cells are at first 
separated by extremely delicate membranes in which no cellulose could be wee 
onstrated, and upon them secundary and tertiary thickening layers are deposite 
No nutri- 
-nucleated 
nsistS 
bridging the space between the priinary wall and the tertiary layer. 
tive material was found between the isolated mother cells, and no non 
reticular resting nucleus was found. The large deep-staining nucleolus © 
of a number of deeply chromatic granules embedded in a faintly staining — : 
A long and well-marked spirem thread occurs in the prophase of eae! 
of the mother cell. The reduced number of chromosomes is 7 oF 8: oii 
12 BEER, RupotF, On the development of the spores of Riccia glauca- el 
of Botany 20:275~291. pls. 21-22. 1906. 
?3 Bot. GAZETTE 37:161-177. 1904. 
14 Bot. GAZETTE 41: 109-138. 1906. 
