TiTK rrrAf'E.T: of .tapax, löO 



that of the cylindrical portion of the foliose ones just alluded 

 to. Ill some cases the upper segments are much complanated, 

 more or less resembling the segments of a narrow form of the 

 foliose type. The structure of such portions has no marked 

 diflerence from that of the foliose type, except that the cryptostomata 

 are entirely absent. 



Relation between the two forms. Sj^ecimens of the filiform 

 type have been distributed by Mr. Okamura under the name of 

 Pelvelia Babingtonii Harv., as No. o7 of *' Algse Japonic» 

 Exsiccaüc." The foliose type was suspected by many people to 

 belong to a different species from the filiform one and some 

 went so far as to consider them to bêlons; to different venera. 



Those wdio consider the two forms to belono- to different 

 species are inclined to regard the foliose branches upon the 

 filiform frond as a parasitic or symbiotic combination. The fact that 

 one of the forms never partially reveals the character of the other 

 stands strongly in fovor of this view. A dimorphic plant may very 

 often show an intermediate or mixed form. But in the present 

 plant none of the ordinarily ramified segments of one type assumes 

 the form of the other in any satisfiictory degree. The upper 

 segments of a filiform frond may be more or less broadened or com- 

 planated but never to such an extent as to link the two types ; 

 in like manner, the segments of the foliose type often consider- 

 ably decrease its breadth but never entrrely lose the characters of 

 that type. When a branch with foliose segments is found in a 

 filiform frond, it always starts from an internodal point with a 

 peculiar mode of insertion, as has been already mentioned (PI. II, 

 fig. 3, 4). 



I am, however, strongly of the belief that the two 

 types belong to one and the same species. We have not been 



