8i 



by F. Schmitz and P. Hauptfleisch. The authors recognize only the genera Amphiroa, 

 Cheüosporum and Corallina out of the old Corallineae verae of Areschoug. When speaking 

 of Amphiroa they call attention to the joints as being "quergezont mit dickem Bundel dicht 

 zusammengeschlossener, in bestimmt alternierender W'eise gegliederten Markfasern". This seems 

 to point to the long and short cells described by Zanardini. 



Setchell and Gardner l ) in their valuable paper on the Algae of Northwestjèrn 

 America (1903) say: "After a long study of the forms of Amphiroa with flattened joints from 

 the western coast of Xorth-America, we have come to the conclusion that they are all forms 

 of one polymorphous species, the forms owing their very considerable differences to variations 

 in the environmental conditions under which they may be found growing .... We do not 

 understand the reasons for referring some of the forms to the genus Chcilosporum, as Yendo 

 has done, since that genus if separable at all from Amphiroa, applies only to a very limited 

 number of species, none of which occur in our territory". 



In my opinion Setchell and Gardner are perfectly right in considering the algae 

 known as Amphiroa tuberculosa, A. Orbigniana, A. Caiiforuica as forms of only one 

 polymorphous species, but I think that this species belongs to the genus Arthrocardia and not 

 to Amphiroa. The reasons why I think so will be shown in the following pages. 



Anatomical. 



The fronds of Amphiroa consist of a tuft of vertical, sometimes horizontally spread, 

 calcified branches which, according to Solms-Laubach, probably arise from a horizontal disc, 

 or at all events from a small 'Keimscheibe', resulting from the first divisions of the eerminatine 

 spore. The branches are as a rule articulated and each joint (articulus) is separated from the 

 next one by a narrower or broader articulation or node (geniculum of Yendo) of non calcified cells. 



The branches, whether ascending vertically or spreading horizontally, have all a central 

 strand of elongated cells and a cortical layer of isodiametrical or ellipsoidal cells. The cells 

 of the central strand have their origin in a layer of meristematic cells at the flat top of the 

 branches, where, in conformity to the mode of growth described by Kny 2 ) for Jania rnbens, 

 Corallina officinalis and C. granifera, they divide as a rule only with transverse walls except 

 at the periphery, where the cells are divided alternately by transverse and by oblique longitu- 

 dinal walls, these latter ones running from the inner part of the lower transverse wall to the 

 apicai part of the outer longitudinal wall. The cells resulting from this latter division are 

 pushed sideways towards the periphery where, by subsequent division, they become smaller 

 and smaller, are divided by transverse and longitudinal walls and form the cortex. This mode 

 of growth proper to Jania and Corallina, is also that of Amphiroa as Solms-Laubach has 

 pointed out, but he showed at the same time that a continuous layer of "Deckzellen" covers 

 the meristematic cells of Amphiroa even at the moment of the most intense growth. This 

 layer of Deckzellen, which is also to be found in Lithothamnion is only now and again renewed 



1) Setchell and Gardner. Algae of northwestern America. Berkeley 1903. 



2) Kny. Bot. Zeitung 1872, p. 705. 



SIBOGA-EXPEDITIE LXI. 



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