ECOLOGY AND TAXONOMY OF Holimeda 



203 



I I I I I I 

 0.5mm 



Fig. 64. Camera lucida drawings of gametangia on their gametophores (stalks), showing 

 the three methods of origin of gametangia in Halimeda. Development from utricles 

 is shown in Nos. 1, 6, 7 and 11 ; from medullary filaments of the segment in Nos. 2, 

 4 and 9; from medullary filaments at the node after fusion in Nos. 3, 5, 8, 10 and 12. 

 Number 1, 3 and 4 are favulosa, Nos. 5-8 are discoidea, Nos. 2, 9 and 10 are scabra 

 and Nos. 11 and 12 are monile. (From Hillis, 1959.) 



The complete development of a zygote to a new thallus has not yet been 

 observed and may possibly involve a different life-form. 



1 . Development of gametangia 



Hillis (1959) described gametangia for favulosa, and listed the 

 following species as those for which gametangia were known : ? cuneata 

 (possibly misidentified), discoidea, gracilis, iyicrassata, macroloba, 

 monile, scabra, simulans and tuna. Subsequently^, gametangia have 

 been described and drawn for opuntia (Kamura, 1966) and cryptica 

 (Graham, 1975), and I have observed them on copiosa, cuneata, 



