Samoa Islands, Graeffe\ — Sandwich Islands, Home\ - Noukahiva n° 2, Herb. Kew\ — 

 Cape York, " Challenger"' '! — Torres Straits, " Challenger" '! — Albany Island, Mueller\ — 

 Queensland, ZWr/c/i! Kilnerl — Norfolk Island, Herb. Mits. Brit.\ — Fakarawa, " Albatross" '! — 

 Rangiroa, Mohegan Reef, " Albatross" '! — Rangina, " Albatross" '! — 



Plants varying in length to about 20 cm., thickly calcified as a rule, especially below. 

 Branched in one plane. Very variable in habit ; long and tapering, or short and flabellate, or 

 forming small tufts ; with all intermediate forms. 



Root bulbous or cylindrical. 



Joints sessile, ribbed, tridentate, cuneate, cylindrical, or discoid, often welded together at 

 base of plant and forming flabellate mass. Lower cylindrical joints sometimes 8 mm. in diameter ; 

 upper cylindrical joints often 8 mm. long, 1 — 2 mm. in diameter; tridentate joints to 14 mm. broad. 



Filaments of central strand either communicate with each other at apex of joint by means 

 of pits of varying size, or, rarely, free throughout. 



Peripheral cells 15 — 50 u. across in surface view. Length very variable, surface of contact 

 slight, up to about Vis °f length. 



forma typica. 



Lower joints deeply calcified, sometimes forming a cylindrical, unbranched stem ; 

 adjacent cylindrical joints connected by lime to form fan shaped base ; upper joints more or 

 less trilobed (fig. 39). 



forma monilis. 



H. monile Lam. 1. c. 

 Joints thick, deeply calcified, moniliform, cylindrical, sometimes compressed ; branched 

 joints cuneate, truncate, often bearing four or five joints along the upper margin (fig. 40). 



forma Lamourouxii. 



H. incrassata var. Lamourouxii J. Ag. 1. c. 

 Lower joints broadly cuneate or trilobed; upper joints more or less reniform, thin, 

 compressed, not deeply calcified, upper margin lobed (fig. 41). 



forma ovata. 



H. incrassata var. ovata J. Ag. 1. c. 



Plant small, generally forming short tufts. Lower joints usually cuneate, truncate ; upper joints 

 small, circular, not deeply calcified, indistinctly ribbed, sometimes slightly lobed on upper margin. 



Filaments of central strand quite entire or connected by small and few pits (figs. 42, 47). 



This form occurs mainly in the Pacific Ocean, but there are also specimens of it in the 

 "Sibog-a" collections. 



'&' 



forma tripartita. 



Lower joints deeply calcified, simple, cylindrical ; upper joints often tripartite, deeply cut, 

 segments cylindrical (fig. 43). 



