480 BULLETIN OF THE BUREAU OF FISHERIES. 



peripheral, radial paniculate tufts of filaments bearing carpospores usually singly at their 

 apices, pericarp thick, dense, joined to the center of the! "nucleus" by numerous sterile 

 strands of filaments. 



About six species, mostly in the Indian Ocean. 



Meristotheca duchassaingii Agardh. Figs. 31 and 32; PI. XCVII. 



Meristotheca duchassaingii, Agardh, in J. Agardh, 187.1, p. 37- 

 Meristotheca f duchassaingii, De Toni, 1897. P- 330. 

 P. B.-A. Nos. 884, 1596. 



Frond flat, expanded, thick, gelatinous, usually subpalmately laciniate, sometimes simple, some- 

 times with marginal proliferations, surface and margins of female plants beset with numerous short, 

 simple, or branched papillae in which the cystocarps are borne, surface of tetrasporic plants smooth or 

 slightly roughened, but not bearing papillae; tetrasporangia zonately divided; color deep rose. 



Florida; West Indies. , 



Occasionally abundant after storms, Bogue Beach, Beaufort, N. C., two small plants dredged from 

 coral reef offshore, August, 1915. 



This species has been observed here from only August to October, but has been collected at points 

 farther south from February to April and may be expected here during any month. It is not known 

 where the plants thrown up on our shores have grown. No specimens were found on the coral reef off 

 Beaufort in May, 1907, or in August, 1914. It seems probable that these specimens grew on sub- 

 merged coral reefs offshore from Beaufort or south of this region. 



This is the northern known limit of the species and of the genus. 



As was noted by Collins (P. B.-A. No. 1596), the tetrasporangia are divided zonately as in other 

 species of the genus, not cruciately, as figured by Agardh. 



Genus 3. Rhabdonia Harvey. 



Rhabdonia. Harvey, in Hooker and Harvey, 1847, p. 408. 



Frond rather terete, sometimes slightly flattened, usually branched on all sides, 

 more or less laxly tubular, sometimes caulescent and thick below, medullary region 

 traversed by longitudinal, branched, anastomosing filaments, cortex composed of 

 rounded angular cells becoming smaller toward the surface; tetrasporangia scattered 

 over the frond among the superficial cells of the cortex, zonately divided; carpogonia 

 occurring singly, immersed in the cortical layer, usually numerous on the fruiting por- 

 tions of the thallus, auxiliary cells less numerous, usually not conspicuous before fertili- 

 zation, usually situated more or less near to the carpogonia and, after union with a 

 process from a fertilized carpogonium, usually fusing with neighboring cells; gonimoblast 

 developed toward the interior of the thallus, forming tufts of filaments radiating in all 

 directions; cystocarps scattered in the branches, immersed, rather prominent, with tufts 

 of branched, spore-bearing filaments radiating from a large central cell intermixed with 

 sterile filaments, inclosed by a thick filamentous pericarp, communicating with the 

 exterior by a pore ; carpospores single or in pairs in the terminal segments of the filaments, 

 often germinating within the cystocarp. 



About 15 species, principally in Australian regions. 



Rhabdonia ramosissima (Harvey) J. Agardh. PI. XCVIII, fig. i. 



Chrysymenia ramosissima, Harvey, 1853, p. 190, pi. 30 B. 

 Rhabdonia ramosissima, J. Agardh, 1876, p. 593. 

 Rhabdonia ramosissima. Be Toni, 1897, p. 363. 

 P. B.-A. No. 993- 



Frond rather compressed, more or less cylindrical above, decompound, usually much branched, 

 6 to 45 cm. tall, main axis 2 to 15 mm. wide, medullary layer very lax, branches alternate, spreading, 



