694 



THE AMEBIC AN NATURALIST [Vol. XL VI 



phvte 

 Anthoc 

 phyta. 



Within the Anthocerotaceaa is an interesting series connecting 

 the small sporophyte of Notothylas with its relatively large 

 development of sporogenous tissue, and the large sporophyte of 

 Anthoceros with a small amount of sporogenous tissue and a 

 highly developed photosynthetic system. 



It is, at present, impossible to say whether or not the type of 

 Notothylas is a reduced one. Cavers believes it is a primitive 

 type from which the more highly developed genera, culminating 

 in Anl/toctros, have been derived. He is inclined to minimize 

 the importance of certain striking features, e. g., the peculiar 

 chlomplasts and the endogenous antheridia, and thinks the dif- 

 ferences between the Anthocerotales and the other liverworts are 

 not sufficient to warrant their separation into distinct classes. 

 He considers the columella of the Anthocerotaceae may be con- 

 nected with the true liverworts through the Sphaerocarpales, 

 which they resemble in a number of particulars. 



It may be noted, in passing, that there is a possibility of a 

 connection of the Anthocerotaceas with some of the lower Mar- 

 chantiales. The Targioniaceae, especially Cyathodium, for ex- 

 ample, show some interesting analogies in the sporogonium with 

 Notothylas, and the gametophytes also agree in the presence of 

 large lacuna?, and the chromatophores of Cyathodium are also 



Cavers 's conclusions may be summarized as follows: From 

 some common ancestral form, ' ' Sphaero-Riccia, " two lines of 

 development diverged, one leading to the Marchantiales, the 

 other to the Sphaerocarpales, which in turn gave rise to the lower 

 Jungermanniales. From some member of the latter, perhaps 

 Fossombronia, all of the leafy liverworts arose. Somewhere near 

 the Sphaerocarpales it is assumed that the Anthocerotales 

 branched off. 



We are inclined to believe that some modifications of this 

 arrangement are likely to be made. It is quite possible that 

 Fossombronia should be removed from the Jungermanniales, and 

 associated with the Sphaerocarpales; and if Cavers 's assumption 

 is correct, that the leafy liverworts (Acrogyme) have arisen 

 from a prototype resembling Fossombronia, this would entirely 

 divorce the two great divisions of the Jungermanniales. 



