CHLOROPHYCEJE 151 



selves gametangia, bearing gametes which conjugate, 

 and so form a zygote. 



The Geographical Distribution. The Acetabulariece 

 are a tropical and subtropical order. Of the 

 fifteen species of Acetdbularia, one however occurs in 

 the Mediterranean and A. Peniculus on the West 

 Australian coast. They occur in all tropical seas. 

 Halicwyne has two species, one (H. Wrightii) in the 

 China sea and the other (H. spicata) on the shores of 

 New Caledonia. Chalmasia has only one species, 

 G. Antillana, and Acicularia is represented alive only 

 in the warm Atlantic (West Indies and South 

 America). 



Dasycladece. 



The Thallus. This sub-order is characterised by 

 the persistence of the whorls of hairs and by there 

 being no distinction between fertile and sterile 

 whorls they are all fertile, except locally in the 

 joints of Cymopolia and by the gametangia being 

 terminal members of the lateral branches, except in 

 Botryophora where they are of lateral origin on these 

 branches. 



In Dasycladus the shoot is nowhere incrusted, and 

 consists of a short erect axial cell without con- 

 strictions or cross-walls, attached to the substratum 

 by a holdfast, and clothed with whorls of branches, 

 about twelve to each whorl. These are again 

 branched in whorls several times, each successive 

 whorl diminishing outwards in length and in the 

 number of branches. At the apex of the ultimate 

 whorl there is produced a single globular sporangium 



