79 



occupied by the conceptacles as a guide, whereby to name my specimens. On the other hand 

 I found that specimens which looked much alike, belonged to quite different species. 



I tried to find an anatomical character, that would prove a surer guide for the deter- 

 mination of the species of this genus and that would be less liable to variation than the form 

 of the separate joints, the manner of ramification, the diameter of the conceptacles or the number 

 and manner in which they appear on the joints; characters which certainly have a great value 

 and have been used till now, but which are not implicitly to be relied upon in all species. 



Lamouroux *), Areschoug '•) and Yendo 3 ) when describing new species have made some 

 very interesting remarks about the node between two joints, but nowhere did I find a systematic 

 and careful study of the nodes. Solms-Laubach tells us only that the node of Corallina consists 

 of one layer of long pericline cells, that of Amphiroa of two layers of pericline cells, while 

 the layer of cortical cells falls off as a rule and is only to be found abnormally in some feeble 

 specimens of A. verrucosa. 



While pondering over this question I remembered the results obtained by Miss E. S. 

 Barton *) while investigating the nodes of Halimeda, and it occurred to me that perhaps the 

 nodes of Amphiroa might also reveal an analomical character, that would be a useful help in 

 classifying the different species. 



In order to understand the structure of the node of Amphiroa it is necessary to recall 

 in a few words the structure of these plants, giving first a little historical survey of all we 

 know about the genus Amphiroa. 



Historical. 



The genus Amphiroa was created by Lamouroux") in 1812 with the following diagnosis: 

 "Plants with filamentous, articulated tufts, branching; branches dichotomous or verticillate, joints 

 entirely separated by a horny substance, naked". After this short diagnosis Lamouroux cites 

 Corallina tribulus Eli. and C. cuspidata Eli. as examples of the new genus adding the following 

 words: "and many non-edited species". I wish to call attention to the fact that Lamouroux in 

 his first note on the genus Ampliiroa mentioned Ampliiroa (Corallina) tribulus Eli. and 

 Amphiroa (Corallina) cuspidata Eli.; they are therefore the types of the genus. In His "Histoire 

 des polypiers coralligènes flexibles 181 6" he places Amphiroa between Cymopolia and Halimeda. 

 Corallina is described before Cymopolia. This shows the value Lamouroux attributed to the 

 articulated appearance of all the above named genera, two of which belong to the Florideae 

 and two to the Chlorophyccae. 



Exdlicher 6 ) 1836 — 47 divided the genus in different sections which were taken up and 

 worked out by Decaisxe. 



1) Lamouroux. Histoire des Polypiers coralligènes flexibles. Caen 1816. 



2) J. E. Areschoug in Agardh's Genera et Species Floridearum 1851, p. 506. 



3) Yendo. Corallinae verae Japonicae. Journ. of the Coll. of Science, linp. Univ. Tokyo. vol. XVI, prt. 2, 1902. — Corallinae 

 i-erae of Port Renfrew. Minnesota Botanical Studies 1902. 



4) E. S. BARTON. The Genus Halimeda. Monogr. I.X. of "Uitkomsten op zool., bot., ocean. en geol. gebied der Siboga-Expeditie". 



5) Lamouroux. Essai sur les gem-es de la fam. des Tkalassiophytes non articulées. Mem. du Muséum. Paris 1S12. 



6) Exdlicher. Genera plantarum cum supplementis. Vindobouae 1836 — 1847. 



