ECOLOGY AND TAXONOMY OF Halimeda 73 



cited and many not cited because of limited space. All the iincited 

 material represented overlaps in geographic range. Institutes providing 

 these specimens were the herbaria of the University of Michigan, Ann 

 Arbor, and the University of California, Berkeley; the New York 

 Botanical Garden; and the British Museum (Natural History), London. 

 Dr W. E. Isaac, then of the University of Cape Town, South Africa, 

 provided liquid-preserved material of H. cuneata. 



Subsequently, Halimeda specimens and collections have been 

 examined from the British Museum (Natural History) ; Royal Botanic 

 Gardens, Kew (algal collections now housed in the former); the her- 

 barium of the Linnean Society, London; Rijksherbarium, Leiden; 

 Botanical Museum, Lund; Botanical Museum, Copenhagen; National 

 Museum of Natural History, Paris ; Botanic Garden, Brussels ; Museum 

 of Western Australia ; Institute of Jamaica, Kingston, Jamaica ; United 

 States National Museum ; New York Botanical Garden ; Duke Univer- 

 sity; Farlow Herbarium, Harvard; University of California, Berkeley; 

 University of Hawaii; University of Michigan; Yale University; and 

 the personal herbaria of Drs R. Tsuda and G. Valet. Professor Y. 

 Yamada kindly loaned the type collections he had made of gracilis f. 

 elegans, incrassata f. distorta and opuntia f. intermedia, the second of 

 which is now the holotype specimen for the species distorta. Professor 

 W. R. Taylor and Dr G. Valet provided authentic material of goreauii 

 and melanesica respectively. 



In addition, many workers have sent specimens from special sites 

 and expeditions. To these I have added my own field collections, 

 principally from the eastern Indian Ocean, Jamaica and Enewetak 

 Atoll in the Marshall Islands, and the especially valuable experi- 

 ence of having made them myself, which has provided understanding 

 of populations of the various species in the reef, including their 

 variation. 



2. Measurement of characters 



The various dimensions recorded, both macroscopic and micro- 

 scopic, have been obtained mostly from dried specimens, some from 

 preserved material, a few from living plants. The measurements on the 

 dried and on some preserved material are smaller than would be obtained 

 using living plants, but for microscopic characters the effect of shrinkage 

 on the measurements for taxonomic purposes is probably generally 

 relatively little. 



For the macroscopic character of segment dimensions, however, the 

 change on drying may be considerable for large segments. In the species 



