9i 



of Lamouroux, I came to the conclusion that tny collection contained A. fragilissima, A. cus- 

 fiidata and A. cyathifera, but that it was impossible to tracé a sharp limit between these so- 

 called species. Sectioning the node of an authentic specimen of Lamouroux of A. fragilissima, 

 I was surprised to find that its structure was exactly identical with that of the node of A. 

 t vat 'hij era ; this latter one being only much more sturdy. I do not attach great importance to 

 this point, whether specimens are more or less slencler, if they agree on all other points, for I 

 have a specimen of A. cyathifera, with some fronds abnormally developed and bearing very 

 thin slender branches, resembling exactly those of A. fragilissima. One long specimen from 

 Banda looked quite like A. fragilissima at its top, like A. aispidata in the middle, and some 

 nodes at its base might be easily taken for nodes of A. cyathifera. 



I therefore think, that it is right to give the name of A. fragilissima to all Amphiroae 

 with cylindrical joints, swollen at their apical and basal part and with distinct periods of intra- 

 nodal growth, clearly visible to the naked eye, even in dried specimens, as very slight constrictions 

 of the frond, with swollen nodes, — not forgetting that the horny nodes shrink much in drying - 

 and with prominent conceptacula. 



The older names may be kept to designate the various aspects which this species can assume. 



f. fragilissima syn. A. fragilissima Lamx. and A. debilis Kütz. 

 slender plants, joints thin, nodes not very conspicuous as a rule. 



f. aispidata syn. A. aispidata Lamx. 



plants stronger than the typical form, but not so strong as 



f. cyathifera syn. A. cyathifera Lamx. 



which is characterizeel by its strong swollen nodes. 



I may perhaps be criticised for sinking the above named species into A. fragilissima, 

 for it seems hard to believe that the delicate plant of Lamouroux should belong to the same 

 species as the coarse A. cyathifera. But we must not forget, that we do not know how or when 

 most Amphiroae were collected. 



Slender forms will sometimes spring from old, thick, creeping branches, but whether therefore 

 all slender fronds are young stages of plants that might become coarse and big if they had 

 had time to live, I do not dare to assume. It appeared to me that mam species had both 

 a slender and a stouter form. The plants growing in deeper water showed, as a rule, a tendency 

 to grow in length, while those growing in shallow water or exposed to the breaking of the 

 waves, dwindled into small, compact, much branching forms. I believe that these different forms 

 belong to only one species, but whether this difference in the form of growth is indeed the 

 result of external inrluences is a question that for many algae must still be settled by careful 

 investigation on the spot where these plants grow. 



2. A. anastomosans n. sp. PI. XIV, fig. 3, 4. 



Tiny plants 1 — 1,4 cm. high, forming a compact tuft on the substratum. Fronds 

 cylindrical, branching dichotomously, branches anastomosing frequently. Joints indistinct because 



