MARINE ALG OF BEAUFORT, N. C. 525 
cystocarps borne in more or less conical, superficial, or slightly sunken conceptacles, 
each conceptacle opening by a single apical pore, carpospores arising from the periphery 
of the fusion cell, the central part of the fusion cell bearing a few elongated, evanescent 
paraphyses; antheridia and cystocarps apparently borne on different plants. 
About 80 species, widely distributed, mostly in warm seas. 
This genus has been variously characterized by different authors and is still not well 
understood. It is distinguished from Lithophyllum chiefly by the fact that each spo- 
rangium communicates with the exterior by a separate pore, so that the surface of a 
mature tetrasporangial conceptacle, when viewed with a lens, looks like a miniature 
pepperbox. The species are exceedingly difficult and can be determined only by those 
who are familiar with them or by comparison with authentic specimens. In some cases 
the same species seems to show different forms on different substrata. 
Lithothamnium sejunctum Foslie (?). 
Lithothamnion sejunctum, Fosile, 1906, p. 3. 
Thallus disk shaped, almost spherical, later confluent and irregular, rather thick, forming masses 
incrusting stones, etc., strongly calcified and closely attached to the substratum, showing slight, con- 
centric zonation; composed of two distinct strata, the lower (hypothallium) composed of several layers 
of cells about 11 to 18 by 5 to 9 mic., the upper (perithallium) composed of several layers of cells, these 
cells squarish, 5 to 7 mic. in diameter or slightly vertically elongated, sometimes slightly horizontally 
elongated; tetrasporangial conceptacles embedded, hemispherical, 160 to 260 mic. in diameter, bearing 
about 4o pores; cystocarpic conceptacles hemisph ericalconical, 200 to 300 mic. in diameter. 
West Indies. 
Incrusting coral rock dredged from coral reef offshore, Beaufort, N. C., May, 1907 (?). 
To this species is referred, with some doubt, an antheridial plant incrusting a part of one piece of 
coral rock, but the determination can not be made with asgurance, since no authentic specimen has been 
available for comparison. It does not seem to belong to any other described species, and has not seemed 
to deserve description as anew species. It is probable that much of the coral rock dredged from the reef 
bears this plant, but only one piece has been available for examination. On this piece the plant here 
referred to occurs alongside Lithophyllum intermedium. From the latter species it is distinguished with 
difficulty. As found here, it has a slightly rougher, less glistening surface than the Lithophyllum. In 
section the two strata are more sharply defined than in the latter form. This species has not been 
recorded elsewhere outside of the West Indies. 
Genus 4. Lithophyllum Philippi. 
Lithophyllum, Philippi, 1837, p. 387. 
Thallus forming a more or less irregular incrusting mass, more or less closely attached 
to the substratum, margin free or loosely attached, undivided or variously lobed, some- 
times bearing irregular proliferations, strongly incrusted with lime, composed of two 
strata, cells rather regularly arranged, radiating toward the periphery, those in the upper 
perithallium smaller than in the lower hypothallium; tetrasporangia borne in sunken 
or somewhat prominent conceptacles, these conceptacles hemispherical-conical, at first 
convex, then losing more or less of the cortex, becoming somewhat depressed, the entire 
conceptacle communicating with the exterior by a single central pore; cystocarps borne 
in sunken or somewhat prominent, convex conceptacles, carpospores accompanied by a 
central mass of short paraphyses. 
About 50 species, mostly in warm seas. 
This genus has been variously characterized by different authors and is still not 
well understood. It is distinguished from Lithothamnium chiefly by the fact that the 
entire tetrasporangial conceptacle communicates with the exterior by a single apical 
