Halicystis and Valonia. 49 



genus from the Sipkonocladaceee, to which Valonia undoubtedly belongs, 

 to the SipJioneae, with which group it agrees in the characteristic chlorophyll 

 layer, and the arrangement of its nuclei. Although I am most strongly 

 inclined to agree with this determination of the position of Halicystis, I 

 confess to a preference for the more cautious attitude of awaiting the story 

 of its reproduction before committing myself to full agreement. I have 

 observed all the details described above by Dr. Schmitz, working quite 

 independently and simultaneously at the material we collected, but such 

 histological details appear to me to be by themselves insufficient support 

 for this step. Since I may fairly claim, however, to have given in several 

 papers unqualified support to Dr. Schmitz's admirable work in establishing 

 the group of Siphonodadacecs* I may take this opportunity of expressing 

 surprise at the small extent to which it has been adopted, and to my con- 

 viction that students who cling to the old system will, after due study, 

 discover the Siphonodadacece to be one of the most natural orders of the 

 green Algae. With regard to the present case I must be understood to 

 express not dissent, but merely hesitation. If we grant the point, the 

 question of its position among the Siphonecs becomes interesting, and on 

 this point Dr. Schmitz's remarks, which I translate, are of great value : 



' The genus Halicystis stands in a somewhat isolated position among the 

 Siphonese, but its vegetative structure, which is all we know of it, recalls that of 

 Botrydiitm.\ This genus, apart from its occurrence in fresh water, is mainly 

 distinguished from Halicystis by its branching filamentous rhizoids. In its simple 

 bladder-like thallus Halicystis is further removed from such genera as Vancheria, 

 Derbesia and Bryopsis, which possess a more or less branched filamentous thallus. 

 A more exact determination of its position among the Siphoneae can only be made 

 when the whole life-history and reproduction of Halicysns has been ascertained.' 



Since Reinke has recently* mentioned the discovery of H. ovalis in 

 Heligoland, it may be mentioned that Dr. Schmitz found it there so long 

 ago as September, 1881, while dredging in the Nordhafen, and he even 

 then came to the conclusion that it belonged to the SipJionecs rather than 

 the Siphonodadaccce, During the winter of 1879-80, Dr. Berthold called 

 his attention to another form obtained also by dredging in the Gulf of 

 Naples on stony ground, rich in corallines. On comparing the preparations 



* Sitzber d. Naturf. Gesellsch. su Halle, Nov. 30, 1878. 



t Botrydiitm possesses in the upper portion of its bladder-shaped thallus numerous 

 small disk-shaped chromatophores, free from pyrenoids, as Halicystis does. The asser- 

 tion of Wille (Engler Prantl. Pflanzenfamilien, i., p. 123), that in the Botrydiaceae 

 only a single much-lobed chromatophore is present, is not correct for Botrydium; 

 Codioluin, which Wille (loc. cit.} places in the Botrydiacece, does not belong to the 

 Siphonea: at all ; the unicellular thallus of C. gregarium possesses a single much-lobed 

 chromatophore with numerous pyrenoids and a single nucleus. 



t Berichte der deutschen botan. Gesellsch. 1889, p. 369. 



