26 SIPHONACEiE. 



III. UDOTEA. Lamour. 



Root fibrous, much branched. Frond erect, stipitate, expanded, flabelliform, more 

 or less incrusted with calcareous matter, concentrically zoned, composed internally of a 

 plexus of longitudinal, subparallel, unicellular, branching filaments. Sporangia "lateral, 

 globose." (Kiitz.). 



The genus Udotea is intermediate between Halimeda and Codium,, differing from 

 the former in habit and from the latter in having the filiform cells of which it is com- 

 posed incrusted with carbonate of lime. The amount of incrustation varies much in 

 different species. In U. flabellata, which very closely agrees in structure with Hali- 

 meda, the calcareous matter forms a solid, smooth, and somewhat polished crust, 

 completely concealing the filaments of which the frond is constructed ; in U. conglu- 

 tinata the lime forms a thin coat round each individual filament, but does not conceal 

 the filamentous structure of the frond ; and in U. Desfontanesii there is scarcely any 

 calcareous deposit, and except in habit the plant is almost a Codium, in which genus 

 it was placed by Agardh. Ten species of Udotea are known, all of them natives of 

 the warmer parts of the sea. Our U. flahellata is found in the Indian Ocean, and I 

 have received U. conglutinata from Port Natal, S. Africa. 



1. Udotea flahellata, Lamour. ; stipes simple, short, terete or sub-compressed, 

 expanding into a broadly flabelliform, simple or lobed, wavy, concentrically zoned^ 

 smooth frond ; the margin either quite entire, undulato-repand, crenate, or deeply 

 lobulate, sometimes proliferous ; surface thickly incrusted ; concentric zones evident, 

 closely set or sub-distant. Dne. Cor. p. 93. Lamour. Pol. Flex. p. 311. Kiitz. Sp. 

 Alg. p. 502. Corallina flahellata, Ell. and Sol. Cor. p. 124. tah.'24: (excellent!). 



Hab. Key West, W. H. H. Abundant between Key West and Cape Florida, Prof. 

 Tuomey. (v. v.) 



Root a fusiform mass of intricately interwoven fibres, one to two inches long. Stipes 

 half an inch to an inch long, terete, a quarter-inch or more in diameter, simple, erect^ 

 terminating in the broadly cuneate or reniform base of the frond. Frond sometimes 

 six inches across, but our specimens are mostly smaller, usually broader than its length, 

 more or less cuneate at base, the lateral margins prolonged downwards in old fronds, 

 which, therefore, are somewhat reniform ; flabellate, either quite entire with a flat 

 margin, or more frequently undulate, lobed at the margin or deeply divided (as Ellis's 

 figure represents) into numerous lacinias, which take the form of the primary frond, and 

 imbricate each other at the edges. The surface is thickly coated with a calcareous 

 crust, and quite smooth ; it is marked at short, but very uncertain intervals, with 

 concentric lines or furrows, much more obvious in some specimens than in others, but 

 always to be found. The substance is as thick as calfskin and leathery to the touch. 



