5i 



Frond flabellate ör suborbicular, from a usually cuneate base, irregularly proliferous from 

 margin or sometimes from surface, zonate, occasionally striate ; dull-green in colour; margin 

 subentire, lacerate, or ciliate. 



Frond filaments parallel, radiating upwards, subcontiguous, monostromatically arranged, 

 dichotomously branched, with uneven supra-dichotomial constrictions-, bearing lateral branchlets of 

 unequal length at irregular intervals, the heads of which are botryoidly or dendroidly subdivided 

 at the apex into somewhat imbricate lobules. Apical divisions of branchlets interlocked, forming 

 a thin continuous monostromatic cortex. Cortex disappearing towards the margin in fimbriate 

 specimens. [Figs. 29 — 31]. 



This species is the well-known Udotea Desfontainii of the Mediterranean Sea. For certain 

 cogent reasons we have been compelled to remove it from the genus Udotea, where it was 

 ill-placed in company with a series of species all calcified. Those species are, we are convinced, 

 derived from such an ancestral form as Udotea javensis (Rhipidosiphon); whereas U. Desfontainii 

 is congeneric with Flabellaria minima (as shown under that species, p. 48), which in its primitive 

 stages manifests a close affinity with Chlorodesmis comosa. And U. Desfontainii itself varies 

 much in the degree of complexity of its structure. Not infrequently the frond is partially and 

 irregularly destitute of cortex, especially towards the margin ; and though the lateral branchlets 

 may be present (Kütz. Phyc. Gen. tab. 42. III.), they fail to develop the lobulate heads, which 

 normally cohere to form the cortex of the frond (fig. 30). Again, the frond may be densely 

 and longly ciliated with a margin of excurrent mam filaments, which are quite free from one 

 another, and bear 110 lateral branchlets (Kütz. Tab. Phyc. VII. tab. 19, ai). And finally in 

 cases of regeneration, where the frond has been partially or entirely cut away, Ernst (loc. cit. 

 tab. VII. figs. 15 — [7) shows that the main filaments of frond or stalk respectively grow out 

 free and destitute of lateral branchlets, indeed much resembling the green free filaments of 

 Flabellaria minima and of Chlorodesmis comosa. 



The synonymy of this species is very extensive and is probably not exhausted in the 

 above list, in the compilation of which we were much helped by Bertoloni's Flora Italica 

 Cryptogama Pars 2. 1S62 p. 47. Bertoloni cites there, and also previously in his Amoeni- 

 tates Ital. 18 19. p. 311, two synonyms, viz., Zannichellia of Micheli and Rhipidion n" 1, of 

 Targioni-Tozzetti, which do not appear to have been published elsewhere. 



The species has been referred to at least nine genera, viz., Ulva, Conferva, Flabellaria, 

 Fucus, Agardhia, Codinm, Udotea, Rhipozoniitm, Olafsenia and Photophobe (subgenus). Of the 

 many synonyms of this plant the oldest Latin binomial appears to be Ulva petiolata Turra 

 (1780?). Consequently the well-known Udotea Desfontainii, being now replaced in its old genus 

 Flabellaria, must in future be designated as Flabellaria petiolata, according to the Vienna code. 

 Indeed this combination (F. petiolata) was actually employed in the present sense by Trevisan 

 in his Xomenclator Algarum 1845. p. 19, a work which was never completed, running to 

 80 pages only and then ceasing abruptly. 



Two authors, Endlicher and Naegeli, have fallen into the error of stating Udotea 

 cyathiformis of Decaisne (Ann. Sci. Nat. XVIII. 1842, p. 106) to be an equivalent of the 



