C. H. Ostenfeld: Contributions to West Australian Botany. I. 7 



wenige Stückchen [Cymod. rotundata, determ. Ascherson] ; das 

 nächste Land war hier 20 Seemeilen entfernt. Weiterhin zwischen 

 den Dampier-Inseln trieben sehr grosse Massen verschiedener 

 Sargassum-Arten, aber von Seegras keine Spur, auch nicht beim 

 Fastlande". 



In F. v. Müller's and A. Morrison's list l of the flora of 

 W. A. we find only the two first recorded species, Posidonia and 

 Cym. antarctica (the Cymodocea is given here under the name of 

 C. zosterijolia F. M.), but not Cym. rotundata. Later P. Ascherson 2 

 added one more species to the flora, viz. Cymodocea isoétifolia from 

 Champion Bay (i. e. off Geraldton), thus making four species. A 

 fifth has recently been discovered, viz. Halophila oralis, which 

 C. Andrews 3 in 1902 found in Freshwater Bay, Swan River 

 Estuary, and still later it was collected at Rottnest Island, off 

 Fremantle. We have thus recorded 5 species, if we regard the 

 free-floating C. rotundata as growing on the West Australian coast. 

 All these five 4 species were also found by me with the addition 

 of two more, viz. Halophila spinulosa and Diplanthera uninervis, 

 both of which are known from the tropical eastern coast of Au- 

 stralia. The sea-grass flora of West Australia now extends to 7 

 species, nearly one fourth of the whole sea-grass flora of the Earth. 



As to their distribution along the extensive coast-line of W.A. 

 our knowledge is very scanty. But it is remarkable that the north 

 coast from N. W. Cape to King Sound seems to harbour no sea- 

 grasses at all. Dr. Naumann emphazises that he did not see any 

 sea -grasses in Dampiers Archipelago (his Cym. rotundata was 

 floating on the surface, not growing), nor at any of the places 

 where I landed (Point Samson, Port Hedland, Broome, Derby) 

 did I find any trace of them. Now it is a well known fact that 

 the north coast of W. A. has a very strongly marked tide, rising 

 in places from 10 to 15 metres. This may be the reason for the 

 absence of sea-grasses, since they cannot endure being laid bare 

 and daily exposed to the burning tropical sun during low tide, 



1 F. v. Müller: List of Extra-tropic West Australian Plants. Revised 

 and augmented by A. Morrison. Western Australian Yearbook for 

 1900—1901, vol. I. Perth 1902. 



2 P. Ascherson: Die geographische Verbreitung der Seegrässer, in: G. 

 von Neumayer: Anleit. z. wiss. Beobacht. auf Reisen. 3. ed. 1905. 



3 C. Andrews: Halophila ovalis Hook, f., an Addition to the Flora of 

 West Australia. Journ. of Proc. Mueller Botan. Soc, Perth, vol. I, 

 No. 10, 1902. 



4 As regard the correctness of the identification of Cym. rotundata see 

 p. 11. 



