738 



THE AMERICAN NATURALIST 



[Vol. XLII 



an excellent account of the sporophytie structures of the Arche- 

 goniates and would by itself form an important volume. As 

 might be expected in a treatise on land plants, and from the 

 author's previous works, the Pteridophytes are the principal sub- 

 jects of study, only two chapters out of twenty being devoted 

 to the Bryophytes. Space forbids even an outline of the great 

 mass of facts brought together, not the least interesting and im- 

 portant being those derived from a study of the fossil forms 

 which of late have attracted so much attention. Very little space 

 is given to the study of the gametophyte, and while no doubt in 

 the problem of the origin of a land-flora the sporophyte is much 

 the more important factor, still we can not but feel that in some 

 cases, a careful study of the gametophyte would have resulted in 

 some different conclusions and would have served as a useful 

 check. Thus all the recent work on the gametophyte of the 

 Ophioglossaceje emphasizes the strong similarity in the repro- 

 ductive organs of these forms ami those of the Marattiacese and 

 makes more probable than ever a real relatim hip < • ml' 

 tween these two orders of eusporangi.de ferns. 



There are recognized three phyla or main developmental series 

 of Pteridophytes, the Lycopods, the ' ' Sporangiophoric Pterido- 

 phytes" and the ferns, excluding I'rmn the lalter the Ophioglos- 

 saeea? which Professor Bower thinks at present had best be treated 

 as a fourth phylum, although he concludes that there is good 

 evidence of ;i more or less evident affinity with the "Sporangio- 

 phoric Pteridophytes." 



The isolated position of the Lyeopods is recognized by Professor 

 Bower, and there certainly is very strong reason, both from a 

 study of the gametophyte and sporophyte, for assigning to this 

 group an origin quite apart from that of the other Pteridophytes. 



The most radieal departure from the ordinarily accepted 

 arrangement of the Pteridophytes is the establishment of the 



he related. The' spora tiLiiophore is defined as ;i more or less 

 elongated vascular stalk upon which sporangia are borne. The 

 sporangiophores are considered to be organs sui generis not a 



