Udoteae 

 Calcified ancestor 



Espcrci ' 



mediterranen P ' Sibo g ae 



Tydemania 

 Gardineri 



P. nodulosus T. expeditionis 



Penicillus 



L'dotea javensis 



U. glaucescens U. subpapillata 



Rhipocephalus U.cyathiformis U. explanata U.conglutinata U. orieatalis 



U. palmetta U. indica 



U. papillosa 



U. spinulosa U. verticillosa U. Wilsoni L'. argentea U. occidentalis 



Halimeda 



U. flabelluin 



In constructing these tables we have endeavoured to allocate the genera and sundry 

 species according to their respective degrees of development along their various lines of descent. 

 But it must not be supposed that we regard the simpler members as being the actual ancestors 

 of the more highly differentiated. They do but indicate some of the stages in the developmental 

 history of the group. 



It will be found that there is very little parallelism between the two groups — calcified 

 and uncalcified, such similarity as does occur being rather of the nature of coincidence. Nor 

 is there much close affinity between them. It might be argued that Flabellaria peliolala, 

 which under the name of Udotea Desfontainü has for nearly seventy years been regarded as 

 an essential member of the genus Udotea, is of close affinity with U. argentea and U.flabellnm. 

 And, apart from the calcification, the similarity of frond-structure is, we admit, very great. 

 But the ancestry of Flabellaria petiolata is unmistakeably revealed by the life history of F. 

 minima (as described and figured by Ernst), which in its simplest stages could hardly be 

 distinguished from a Chlorodesmis. The uncalcified genus Flabellaria has therefore a totally 

 different origin from that of the calcified true species of Udotea, which as the table shows are 

 easily traced back to a simple little calcified flabellate ancestor like U. javensis. 



Chlorodesmis and Rhipidodesmis {Chlorodesmis caespitosa]. Agardh) are the most primitive 

 extant forms of the Flabellarieae. Chlorodesmis certainly indicates the ancestry of Flabellaria, 

 and probably that of the flabelliform genera, Avrainmllca, Rhipiliopsis, Rhipilia, and Clado- 

 cephalus; possibly also that of the Codieae (Codium and Pseudocodium). We are in doubt as 

 to the position of Boodlcopsis, whose peculiar habit is unique in the group. 



