94 



In the opinion of Rosenvinge (Ann. sci. nat., ser. 7, voi. 19, p. 93, 

 1894; and mysclf (cfr. Setchell, Proc. Amer. Acad., voi. 26, pp. 208 

 et seq., 1891), the Phyllarìa lorea (Bory) Kjellm. is only the voung 

 form of Ph. dcnnatodca (De la Pyl.) Le Jolis, or what \ve have both 

 called Saccorln\a dermaiodea (De la Pyl.) J. Ag. There seems to be 

 reason for supposing that Ph. lorea, which Kjellman (Algae of the 

 Arctic Sea, p. 226, 1 883) claims as a separate species and gives 

 reasons at length, may be a case of arrested development or what 

 we may cali l'or brcvity's sake, a vernai form, similar to the Phvl- 

 litis lorm of L. saccharina. Farther study may even prove it to have 

 some claims to be considered as a distinct variety, for Kjellman 

 found developing zoosporangia (loc. cit., p. 227) on one individuai. 



Ali these and other similar cases, lead me to believe that the 

 Renfrewia parvula is not a primitive form in the sense of being a 

 form which developed early in the phvlogeny of the Laminarìa-phy- 

 Inni, but a form which may have originated later through environ- 

 mental condilions which prevented its developing the characteristics 

 of a fully developed and mature species of the genus Laminaria. 

 Similarily, it seems to me that the discoid holdfasts of L. solidun- 

 gula and also of L. ye\~oeusis are not primitive but modified hold- 

 fasts. Ali these forms seem to be part and parcel of the genus La- 

 minaria, not leading up to really distinct genera other than that 

 and the characters selected by Griggs do not seem to afford satis- 

 factory lines of cleavage to be taken advantage of to satisfactorily 

 split up the genus Laminaria as now commonly accepted. 



Reinke has published in igo3, in bis « Studien zur vergleich- 

 enden Entwickelungsgeschichte der Laminariaceen » (Kiel), detailed 

 arguments for considering the Laminariaceae of monophyletic origin 

 and with his views I fìnd my own in general agreement. On p. 5r, 

 however, he considers Laminaria solidungula to be the primitive form 

 (« Urform ») and again on p. 55, he suggests something of the phy- 

 logenetic sequence of the origins of different more highly differentia- 

 ted forms. I cannot agree with him in considering L. solidungula 

 to be more primitive than some member of the L. saccharina - 

 group and carry my belief similarly to ali forms with discoid hold- 

 fasts. The occurrence of rudimentary hapteres in Cymathacre and 

 in Laminaria ephcmera seems to mitigate against this view, and the 



