■ïil. ir but 1 ■ ute appendages occur also in U. verticillpsa, and are 



1 apitate appendages are borne upon the main filaments of the 



at numbers, and less numerously in U. flaóellum ;in<l Flabel- 



minal swellings <>r ramifications cohere together t<> form a 



ering the t\\" surfaces oi the frond, being much calcified in U. argentea 



and uncalcified in Flabdlaria petiolata. \ somewhat similar cortex isprod 



ition '»t' the apical ends of the lateral outgrowths which arise from 

 fïlaments in the stipites of Penicillus^ Rhipocephalus and all the species of Udotea, 



monosiphonous species U. javensis and (', papil losa. 



Pseudo-lateral branches play a similar part in the formation of the labyrinthine 



the uncalcified genus Cladocephalus. Such branches are of dichotomous origin, but, 



ihort, assume a lateral position and, undergoing much repeated dichotomous division, 



the characteristic intricated cortex. Pseudo-lateral branches also occur in Rhipilia^ bul 



a different function. The) do nol form a cortex, but bear each a terminal digitate tenaculum 



rown, employed either for linking on to an adjacent filament, or perhaps for thrusting it 



Pseudo-conjugating filaments occur in Rhipiliopsis, consisting of short 

 i arising laterally, one from each of two neighbouring fïlaments, and meeting end-on, 

 ne\ ng however but always remaining divided by a septum. 



Habit. The habit is often characteristic of the genus. Among the different forms 

 med are the following: flabellate {Udoted)\ Babelliform {Avrainvillea, Flabellaria, 



yathiform {Udotea cyaihi/ormis, Rhipiliopsis^ Rhipilia tenaculosa, R. orientalis, 

 Cladocephalus excentri apituliferous [Penicillus, Rhipocephalus) \ scopulaeform [Cladoce- 



phalus scoparius ; glomeruliferous [Tydemania expeditionis) \ catenulate [Halimeda ; caespitose 

 'oroa 



1 omparative modes of growth in different genera. Growth in length is 



limited in some genera, continuous in others, and interrupted in others again. In Penicillus the 



th in length of the stipes is terminated by the formation of the coma. In Rhipocephalus 



wth in length is not terminated by the formation of a coma; hut both stipes (rachis) 



and coma ntinuously, though slowly, added to at the apex. In Tydemania the growth 



main axis is periodically interrupted during the formation of the glomeruli. In 



•ral strand of filaments ceases growth for a while after the formation of each 



In ■ the growth of the stipes is terminated by the formation of the flabellum ; 



om< shows signs of interrupted growth at the /ones (see p, 104) and 



■us. 



-dichotomial constrictions an- characteristic of the Udot< 



not occur in all the genera: for instance in Rhipilia and Cladocephalus 



also in Udotea flabellum and U. verticillosa. When present they 



the very base of the two branches emerging from the dichotomy 



tl' ijority of genera: — Chlorodesmis Hildebrandtii, Avrainvillea, 



•na (according to Ernst), Rhipidodesmis, Callipsygma, Boodleopsis, 



