H 0.1mm 



Fig. 17. Appearance of the' surface of a portion of a Halimeda segment, sho^\dng some 

 of the range in size and pattern among the different species. Each polygon or circle 

 represents the surface of a peripheral (primary) utricle, and is the tip of the cortical 

 branch system. Some of the variations which occur with age are shown in Nos. 14, 

 18, 20 and 23. Taxonomic characters shown include size; whether the utricles adhere 

 laterally, or separate as in Nos. 10, 13, 16 and 19, or remain somewhat attached 

 but separate easily as in Nos. 14, 17, 24 and 25; the presence of spines. No. 5; 

 and the presence of thickening as in Nos. 2,23 and 25. (I) H. cuneata, regular segment ; 

 (2) H. cuneata, from a cushion segment showing the thickened walls which are fairly 

 common in these small segments; (3) H. opuntia; (4) H. copiosa; (5) H. scabra 

 showing the spines as small circles in the polygons; (6) H. lacunalis; (7) H. gracilis; 

 (8) H. lacrimosa; (9) H. tuna; (10) H.fragilis; (11) H. discoidea; (12) H. taenicola; (13) 

 H. micronesica from 'a mature segment; (14) H. micronesica from a very yornig 

 segment, showing slight adhesion of peripheral utricles; exact age unknown, but 



