MacMillan: OBSERVATIONS ON PTERYGOPHORA. ial 
japonica,* Agartht suggested that the type specimen was 
nothing other than a mid-lamina of Plerygophora. While this 
notion of Agardh’s was incorrect, a comparison of specimens or 
reference to Suringar’st plate of Lamznaria japonica will make 
it clear how natural might have been such a supposition on his 
part. One also finds in the genus Lamznarva forms suggesting 
the pinnate disposition of lamine in Plerygophora. Such a 
plant is figured and described by Kjellman§ under the name of 
Laminaria radicosa. In this plant lateral outgrowths occur 
upon the stipe below the lamina in quite the same position in 
which they are developed in Pterygophora. They are not, 
however, functional as additional laminz, nor do they particu- 
larly increase the photosynthetic vigor of the plant. Lamznarza 
radicosa may, nevertheless, be regarded perhaps as showing a 
transition to the type of Plerygophora. 
_ There are some objections to the classification of Pterygo- 
phora with Alaria. Among these, the character of the young 
plant should be given weight. In A/arza the midrib is dif- 
ferentiated at an early stage and is exceedingly distinct in plants 
only two centimeters in length, while in Pterygophora plants 
35 centimeters in length show the midrib but indistinctly in 
the basal portion of the lamina. Anatomically Plerygophora 
conforms to the type of the Laminariez in the general character 
of its tissues, differing in some marked particulars from A/arva, 
although resembling the latter in absence of mucilage canals— 
structures which are present in most species of Lam/naria. 
The distinction of outer and inner cortex which is not always to 
be made out in Al/arza is very clear in Pterygophora. Upon 
the whole there would seem to be little objection to the classifi- 
cation of Plerygophora in the tribe Laminariee. Taking every- 
thing into account, however, it will perhaps be best to consider 
the genus as transitional between the Laminariee and the 
Alariidee. 
An examination of the anatomy of Plerygophora seems 
further to strengthen the view of its close relation to Laminaria, 
while the differentiation of its organs no doubt makes it readily 
* Areschoug, J. E. Phyceae Capenses, 29. 
tf Agardh, J. G. Proc. Soc. Phys. Lund. Bot. Notiser, 1883: 108. 1883. 
t{Suringar, W. F. R. Algae Japonicae, p/. 77. 1870. 
4 Kjellman, F. R., and Petersen, J. V. Om Japans Laminariaceer. Ur Vega- 
Expeditionens Vetensk. Iakttagelser., 4: 259, p/. zo. 1885. 
