182 C. H. Ostenfeld: 



V. — Australia fi r/roiip (5 species), i.e., species found along the 

 western and southern coasts of Australia and all round Tasmania, 

 some extending as far as Queensland and New Zealand. 



VI. — Mediterranean groirp (2 species), i.e., species occurring in 

 the Mediterranean and reaching the Atlantic coasts at the numtli 

 of the Mediterranean. 



VII. — North-Facific (jronp (2 species), i.e.. species occurring 

 along the North-Pacific coasts of North America, and (one species) 

 also along the coasts of Japan. 



VIII. — North-ttmperate group (2 species), i.e.. species occurring 

 in the northern (cold and temperate) parts of both the Atlantic 

 and the Pacific oceans. 



Of these eight groups. I. -IV. are tropical. V.-VI. icann-femperate 

 (or subtropical), and VII. -VIII. temperate. 



I. The Indo pacific yronp consists of 7 species — viz. : Halophila 

 ovalis; Enlialus acoroides; Thalassia Hemprichii ; Cymodocea isoeti- 

 folia; Cymodocea rutundata ; Cymodocea serrulata ; Diplanthera 

 uninervis 



Halophila ovalis has the widest area of distribution, as it reaches 

 the western and southern coasts of Australia. Taken as a whole, 

 the geographical area of this group is larger than that of any other 

 (perhaps except that of Zostera marina). It is probable that the 

 group represents the direct offspring of tlie old types of sea-grasses 

 and that it inhabits their old area. 



II. The Malayan group has four species, viz. : Halophila devi- 

 piens, Halophila ovata, Halophila Beccarii, Halophila spinulosa. 

 All these species are rare, being found only in a few places, but 

 it is pi'obal)le that further search will show that they have a wider 

 distiibution. so that the group may perhaps be included in the 

 Indopacific one. 



[It is worth noting that //. spinulosa differs widely from all other 

 species of Halophila. and is probably of great age. Being of 

 quite characteristic habit, and also conjparutivcly cuns])ieuous. it 

 is not probable that it has been overlooked im the continiental 

 coasts of the Indian Ocean, from which it has not yet been re- 

 ported; it seems, in fact, to be restricted to the .Malay legion.] 



HI. The East-African group has only two niciiibers — viz. : Halo- 

 phila stipulacea, Cymodocea ciliata. They aic routined to the 

 Red Sea and the western side of the Indian Oeean. (C. ciliata has 

 been reported from .Australia in eiror for ('. .^erndata.) 



