164 CEYLON PEARL OYSTER REPORT. 



H. gracilis, Harv., with sporangia (see below, p. 165). 



Geogr. distr. : Indian and Pacific Oceans. 

 H. opuntia, Lam. 



Geogr. distr. : Tropical zone. 



PH,EOPHYCE;E. 

 Padina commersonii, Bory. 



Geogr. distr. : Indian, N. and S. Pacific and tropical Atlantic Oceans. 



Dictyota, sp. 



Sargassum ; a fragment only, but Professor Herdman's notes show that a species 

 is present in great profusion on some parts of the pearl banks, and is of importance in 

 connection with the attachment of the young pearl oysters. 



FLOPJDEiE. 

 Galaxaura obtusata, Lam. 



Geogr. distr. : Warm Atlantic and N.W. Pacific Oceans. 



G, rugosa, Lam. 



Geoor. distr. : Warm Atlantic, Indian and Pacific Oceans. 



Aclinotrichia rigida, Decne. 



Geogr. distr. : Red Sea, Indian and N. and tropical Pacific Oceans. 



Brachydadia marginata, Schmitz. 



Geogr. distr. : Indian, Pacific and tropical Atlantic Oceans. 



Gastroclonium opuntia, Kutz. 



Geocx. distr. : Indian Ocean. 



Hypnea musciformis, Lam. 



Geogr. distr. : Mediterranean Sea, tropical and sub-tropical oceans. 



Dr. Herdman informs me that this species is of a green colour when alive, and that, 



along with a species of Cladophora, a Ceramium, Chcetomorpha and Polysiphonia, 



all infested with Cyanophycese, it forms great masses, mostly of a green colour, on 



parts of the Cheval and Modragam banks, where it has many young pearl oysters 



attached to it. 



Laurencia sp. ; young plants. 



Neurymenia fraxini folia, J. Ag. 



Geogr. distr. : Indian Ocean. 



Polysiphonia sp. ; sterile. 



Dasya sp. ; fragment with tetraspores. 



Ptilota- fergusoni, Grun. 



Geogr. distr. : Ceylon. 



Haloplegma preissii, Sond., var. Jlabelliformis, Harv. 



Geogr. distr. : Australia, Tasmania. 



