ECOLOGY AND TAXONOMY OF HaUmeda 89 



16. A small "cushion" segment to 1-5 mm long, 5-5 mm broad inter- 

 posed between some or all of the segments (Figs 18, 61) H. cuneata, p. 124 



16. Small "cushion" segments absent . . . , . . . . . . 17 



17. Mature plants small, not exceeding 5 cm in length; the segments of 

 at least the upper half of the plant spherical or tear-shaped, to 

 5 mm long, 5 mm broad and 5 mm thickness ; secondary utricles 

 capitate (Fig. 20, No. 12), supporting 6-18 peripheral utricles . . 



H. lacrimosa, p. 147 



17. Mature plants larger ; segments flat or somewhat contorted but not 

 spherical . . . . . . . . . . . . . . . . 18 



18. Average surface diameter of the peripheral utricles exceeding 



120 (Jim 19 



18. Average surface diameter of the peripheral utricles less than 



120 (Am 20 



19. Segments large, to 31 mm long, 42 mm broad, not friable; colour 



on drying brownish-green; calcification rather light H. gigas, p. 132 



19. Segments smaller, to 15 mm long, 24 mm broad, friable; colour on 

 drying white or pale greenish-white ; calcification moderate 



H. macrophysa, p. 134 



20. Peripheral utricles each projecting into a central spine H. scabra, p. 127 



20. Peripheral utricles with smooth outer surface . . . . . . 21 



21. Node consisting of a single medullary filament . . H. cryptica, p. 154 



21. Node consisting of several to many medullary filaments . . 22 



22. Secondary utricles noticeably inflated, generally exceeding 90 (xm 



in diameter (Fig. 20, No. 11) . . . . H. discoidea, p. 136 



22. Secondary utricles less than 90 (i.m in diameter . . . . . . 23 



23. Tertiary utricles averaging 110 (j,m or more in diameter, with 

 length two to three or more times the diameter . . H. taenicola, p. 139 



23. Tertiary utricles averaging less than 110 iim. in diameter and 

 length not more than twice the diameter of the utricles . . . . 24 



24. Diameters of secondary and tertiary utricles swollen in comparison 

 to diameters of medullary filaments, utricles noticeably contracted 



at their bases . . . . . . . . . . . . . . . . 25 



24. Diameters of secondary and tertiary utricles not appreciably 

 greater than diameters of medullary filaments, secondary and 

 tertiary utricles not conspicuously contracted at their bases . . 26 



25. Segments, at least those of the upper half of the plant, predomi- 

 nantly reniform to discoid ; peripheral utricles generally exceeding 

 50 (i,m in surface diameter; nodal fusion in small units, for a short 

 distance or complete . . . . . . . . . . H. tuna, p. 122 



25. Segments predominantly subcuneate to obovate; peripheral 

 utricles generally 50 (xm or less in surface diameter ; nodal units ' 

 fusing completely in twos and threes ; units entangled and adhering 

 strongly for 80-150(-280) (j.m . . . . . . H. lacunalis, p. 129 



26. Nodal filaments remaining separate although adjacent filaments 



may adhere slightly . . . . . . . . . . H. fragilis, p. 151 



