278 K. YENDO. 



Although I am not able at present to give any account of 

 the embryonal stages of the present species, it is highly inter- 

 esting to compare it with Porphyropsis coccinea Rosenv. and 

 Porphyra najadum Anders. Anderson's plant has a paren- 

 chymatous, cushion-shaped base instead of the fibrous strands 

 of ordinary Porphyra. Rosenvinge's has a similar sort of base 

 while it is still young; but the parenchymatous tissue becomes 

 hollow inside as the plant developes further, and finally bursts 

 open to form a single-layered membranous frond. Our form 

 may be regarded, in this particular respect, as an intermediate 

 link between the two. 



To explain why I have retained the generic name Wildemania, 

 a few remarks will not be superfluous. In the so-called "miniata" 

 group of the distromatic Porphyra, there are often found mono- 

 stromatic areas, especially at the tip of a frond. In Porphyra 

 ahyssicola, the frond is sometimes monostromatic and sometimes 

 distromatic. On these grounds Rosenvinge combined Wildemania 

 with Porphyra. Hus, Setchell, Gardner, etc., followed the con- 

 ception. It is a fact that in these forms the monostromatic area 

 is mostly on the apical part of the frond, i. e., the part formed at 

 an early stage of development, or they are monostromatic be- 

 fore the fronds attain to maturity. This shows that the mono- 

 stromacy or distromacy of a frond is dependent on the age of the 

 plant. The species of the monostromatic Porphyra may be re- 

 garded as a group which retains the primitive character for the 

 whole life, and those of Wildemania as more advanced forms. 

 The ''miniata" group, as well as P. ahyssicola, should be taken 

 as an intermediate stage of the two extremes. If two or more 

 different types are to be amalgamated into one because there 

 are intermediate forms, such genera as Enteromorpha and 

 Monostroma should have been reduced to Ulva. This was a 

 view once held by Le Jolis, but rejected by modern algo- 

 logists. 



