GRASS-GREEN SEAWEEDS 57 



GENUS Anadyomene 



A. flabellata. Frond composed entirely of brancning filaments, 

 which unite and form an undulating, rigid membranaceous surface, which 

 'seems like a network of veins. The species grows in bunches on short 

 stems in the fissures of tidal rocks, and at first view resembles young 

 Ulva. It is a very curious and beautiful alga, and should be examined 

 with a glass. It is one inch to four inches in diameter when full- 

 grown. (Plate V.) 



This order also inhabits only tropical or subtropical seas. It 

 is placed in this group, although only the main axis is unicellu- 

 lar. The one-celled axis is surmounted or encircled by whorls of 

 minute filaments or branchlets (ramuli), which protrude through 

 small holes and are either persistent or deciduous. In the latter 

 case the fallen filaments leave disk-like scars on the stem. 



GENUS Acetdbularia 



A. crenulata. This little alga resembles a mushroom of the 

 Agaricus variety or gilled species, and so is easily identified. It is thinly 

 incrusted with lime and is found on rocks and coral, within tide-marks, 

 on the Florida reefs. When full-grown the stipe is two to three inches 

 long and the cap one half of an inch in diameter. (Plate VI.) 



GENUS Dasycladus 



Fronds destitute of calcareous matter, soft, cylindrical or club- 

 shaped; single unicellular axis, beset with fine filaments or 

 ramuli. 



D. ocddentalis. Frond club-shaped, one to two inches high, one 

 half of an inch or less in diameter ; covered with whorls of fine filaments, 

 making the fronds almost spongy ; substance soft but tough ; dark 

 green. These plants have been compared to foxes' tails. They grow 

 in bunches on rocks between tide-marks. (Plate VI. ) 



GENUS Cytnopolia 



C.barbata. Frond branched, dividing regularly in pairs; thickly 

 incrusted with lime. Annular constrictions at short intervals give the 

 branches the appearance of strings of beads. Each section is covered 

 with pores or scars of fallen ramuli. The branches terminate in tufts 

 of fine filaments. 



