164 MiXXESOTA BOTANICAL STUDIES. 



Ord. Floridearum. 2:427. 1852. Kiitz. Tal). Phvc. 8:42. pi. 89. 

 1858. 



PLATE XXIV. FK;. 1. 



Frond terete, flattened below on drying, subcanaliculate, above 

 terete, dichotomous, subpinnate, with very numerous lateral pro- 

 liferations covered with a mealy, somewhat uniform crust of lime ; 

 apices divaricate, obtuse, purplish when young. 



Two collections. Tahiti. Societv Islands. September. 1910. 

 (J. E. T.) 



The frond is small, 4-6 cm. high, .7S mm. thick at base, with 

 the principal branches about .5 mm. thick. It branches repeatedly 

 in a dichotomous manner with short internodes (3-8 mm.) from 

 which spring very many lateral proliferations which may be simple 

 or forked. The calcareous incrustation is somewhat mealy, be- 

 coming firmer in the older parts of the frond, but not forming a 

 continuous smooth layer. The tips are free from lime for a dis- 

 tance of one or two mm. The central cylinder is somewhat firm 

 and thick in the older parts of the frond, composed of terete fila- 

 ments of two sizes ; the larger are composed of cells about 200-225 

 mic. long and 10 mic. wide at the lower end, over 20 mic. wide 

 about the middle, and 15-17 mic. wide at the top where the filament 

 branches, giving off one of the cortical branchlets. The smaller 

 medullary filaments are cylindrical, about 4 mic. in diameter, little 

 branched. They arise first from the lower cells of the cortical 

 branchlets, later from nearer the top and even those just below the 

 corymbose summit. The cortical branchlets are 250-400 mic. long, 

 several times dichotomous near the base. The basal cell is nearly 

 cylindrical, about 10x35 mic. Those just above it are slightly 

 longer and narrower, becoming elliptical towards the summit of the 

 branchlet, expanding suddenlv into the several times divaricately 

 di- or trichotomous corymb of short ellijisoidal cells (about 4-6 

 mic), the outer ones often bearing a very small conical tip cell 

 (2x3.5 mic.) The cystocarps are large with a scanty involucre of 

 the tips of the vegetative filaments. 



Liagora tenuis J. x\g. Anal. Algol. 3:101. 1896. De Toni. 

 Syll. Algar. 4:89. 1897. 



PLATE XXIV. FIG. 2. 



Frond terete, dichotomously decompound, subcorymbose. with 

 obtuse apices, the whole lower part covered with a continuous cal- 

 careous crust marked with scattering denuded dots (cystocarps), 



