90 L. HILLIS-COLINVAtrX 



26. Nodal filaments fusing in small groups although the occasional 

 filament may remain separate . . . . . . . . . . 27 



27. Mature thalli relatively small, usually 13 cm or less in length; 

 segments also relatively small, with length usually less than 6 mm, 

 width usually less than 1 1 mm . . . . . . . . . . 29 



27. Mature thalli larger, generally exceeding 13 cm in length; seg- 

 ments also larger with length to approximately 16 mm, width to 

 about 25 mm . . . . . . . . . . . . . . . . 28 



28. Plants to about 20 cm tall, generally growing erect, thallus some- 

 what heavy-set ; nodal fusions mostly in twos or threes, the fusions 

 within the units being for a short distance or complete . . 



H. bikinensis, p. 141 



28. Plants to 70 cm long although they may be considerably shorter, 

 frequently pendant from rock, branches relatively long and 

 somewhat sparse so that overall appearance of thallus is of 

 delicacy ; nodal filaments most commonly fusing in small groups for 



a short distance only . . . . . . . . . . H. copiosa, p. 118 



29. Segments predominantly slightly reniform or transversely oval; 

 average diameter of peripheral utricles in surface view about 



16 (xm or less . . . . . . . , . . H. velasquezii, p. 117 



29. Segments predominantly other shapes, average diameter of 

 peripheral utricles in surface view 22 [xm or greater . . . . 30 



30. Segments generally longer than broad, except for those bearing 

 branches; segments in upper part of plant flattened- cylindrical to 

 cylindrical; plants often bushy and in shallow water tending to 

 grow erect; nodal fusion mostly in pairs but also in threes with 

 filaments occasionally separate ; of Indo-Pacific distribution 



H. minima, p. 113 

 30. Segment length generally equalling width or somewhat broader in 

 upper part of thallus; plant growth form somewhat pendant; 

 fusion units of nodal filaments in pairs ; of Atlantic distribution 



H. goreauii, p. 112 



2. List of Indo-Pacific species of Halimeda 



Section Rhipsalis H. renschii 



H. incrassata ^- velasquezii 



H. cylindracea ■" • (^opiosa 



H. stuposa H. distorta 



H. borneensis 



H. macroloba Section Halimeda 



H. tuna 

 Section Opuntia jj cuneata 



H. opuntia H. lacunalis 



H. minima H. gigas 



