io5 



coral sand in which the plants grow, often forming a bulbous mass, as is seen in the figure 

 of U. flabellum (PI. III. tig. 26). 



Cell-contents. For want of living material, we are only able to state that starch 

 occurs in great abundance in the parts of the plant which are not exposed to light, namely 

 in the rooting parts, and in thickly calcified sterns and fronds, for instance in the frond- 

 filaments of U. flabellum. 



As to the distribution and character of the chromatophores, we are unable to offer 

 any remarks (save in relation to the pores of the calcareous sheath p. 102). 



Fruit. The sporangia of Udotea are unknown. So-called zoosporangia have been 

 described and figured for U. Desfontainii, a species which we exclude from the genus Udotea, 

 and describe under the name Flabellaria petiolata (p. 48). As stated under Flabellaria, these 

 zoosporangia require confirmation. In Udotea proper the sporangia may be expected to occur 

 at the apices of filaments at the margin or on the surface of the frond, as in Avrainvillea 

 or 'Halimcda. We have been unable to find any tracé of sporangia in Udotea, unless it be 

 that the blind apices referred to above in the paragraph on Fusions (p. 104) represent the 

 bases of old sporangiophores. 



Geographical Distribution. Udotea flourishes principally within the tropical zone, 

 but is not confined thereto, for U. orientalis extends to Natal and U. javensis occurs in 

 Japan. Few details are available respecting the habit and marmer of growth, but they appear 

 to flourish on coral reefs and sand, even down to a depth of 100 meters below sea level. The 

 geographical distribution of each species will be found under its own name. 



Systematic. 



Up to the time of publication of J. G. Agardh's account of Udotea in Till Alg. Syst. 

 (loc. cit.), there was no attempt to classify the species of this genus according to groups. This 

 author however divides the genus, as mentioned above, into four sections, founded on differences 

 exhibited by the filaments of the frond as regards straightness, juxtaposition, manner and 

 degree of calcification and the presence or absence of cortex and of connecting fibulae or 

 lateral branchlets. The four sections are called Palmettae, Incrustatae, Fibuliferae, Corticatae. 

 The first of these, Palmettae, contains three species - U. glauceseens, U. palmetta J. Ag. 

 non Decaisne (= U. orientalis A. & E. S. Gepp), and U. infundibulum Suhr (= U. cyathiformis 

 Decaisne) ; the second, Incrustatae, contains only U. conglutinata ; Fibuliferae contains U. 

 Desfontainii (= Flabellaria petiolata Trevis. see p. 48), and U. peltata J. Ag., which as we 

 show on p. 45 must be regarded as representing a new genus, Rhipiliopsis. Corticatae contains 

 only U. Jïabellata. Six other species are mentioned by name only, being unknown to the 

 author. As Agardh omitted to borrow and examine Decaisne's type of U. palmetta, and 

 evidently overlooked the original figure, he had only Dkcaisne's short and incomplete descrip- 

 tion to rely upon. Thus he feil into the error of regarding l \ suborbiculata Sonder as syn- 

 onymous with U. Palmetta Decaisne. The plant described by Agardh as U. Palmetta, must, 

 we are convinced, be referred to our U. orientalis. 



The species of Udotea are roughly separable into two groups, as Ellis and Solander 



SUIOGA-EXPEDITIE LXII. 14 



