136 



L. HILLIS- COLIN VAUX 



segment surface, the latter resulting from the extremely large peripheral 

 utricles and their separation by calcium carbonate partitions. From 

 favulosa it can be separated macroscopically by its habit including the 

 absence of the bulbous holdfast of the Rhipsalian species, and by the 

 morphology of its segments. Reniform segments commonly occur in 

 macrophysa, the plants themselves usually being compact and less than 



Fig. 40c. H. macrophysa. Fertile specimen, pendant from coral rock, Pulau Stupai. 

 "Growths" on most of the segments are gametangia supported by gametophores 

 (Fig. 64). Average width of segments is 13 mm. (Photograph by K. Riitzler, repro- 

 duced with permission.) 



10 cm tall, whereas in favulosa trilobed or cylindrical segments pre- 

 dominate, and the plants are attenuate and to 22 cm in height. In 

 microscopic details the cortex in both species is rather poorly developed, 

 but the node structure is different. 



Halimeda discoidea Decaisne 

 Figure 41. 



Halimeda discoidea Decaisne (1842), p. 91; De Toni (1889), p. 527; Collins 

 (1909-1918), p. 400; Howe (1907), p. 495, Plate 25, Figs 11-20, Plate 26; 

 Taylor (1928), p. 82, Plate 10, Fig. 17; Plate 11, Fig. 23; Taylor (1950), 



