MARINE ALG OF BEAUFORT, N. C. 523 
aa. Thallus consisting of an irregularly spreading, calcareous mass incrusting stones, coral, 
pn othetsalowkgn $s weiae: delta dtnh ate Nett 245 eR Tad Qare, Ihe es, . C. 
c. Mature tetrasporangial conceptacle having a i we opening for each sporangium 
.3. Lithothamnium (p. 524). 
ce. Matuee ieeraneraieial reotien siiiete ees a dete apeuitie ieeatiet which all the 
sporangia discharge, vegetative tissues usually in fairly regular layers. .4. Lithophyllum (p. 525). 
Gqa@ebnetits erect, segmented wprancGhed 4) Avestan gaan veiea tivtebieliee witerciie welt cia une e ciate, le lee d, 
d. Cystocarps forming wartlike protuberances, scattered over the surface of the seg- 
TUCTIES!.. 13. gre ap teen ti MLEt pA REE Ey epee” sachet tse MLaeTs, «fe lle 5. Amphiroa (p. 526). 
dd. Cystocarps immersed in the swollen apices of some segments................6. Corallina (p. 527). 
Genus 1. Melobesia Lamouroux. 
Melobesia, Lamouroux, 1816, p. 313. 
Thallus forming a small, flattened disk, attached to the substratum by the entire 
under surface, strongly incrusted with lime, composed of a single, undifferentiated 
stratum, consisting of numerous rows of cells disposed in a radiating, fanlike arrange- 
ment, with larger, more-elongated cells (so-called “hair cells’’ or ‘‘heterocysts’’) present 
among the ordinary cells; tetrasporangia zonately divided, borne in flask-shaped con- 
ceptacles formed by the separation of thallus cells, these conceptacles borne superficially 
or somewhat immersed in locally thickened portions, opening to the exterior by a single 
central pore, or by a separate pore situated above each tetrasporangium; antheridial 
and cystocarpic conceptacles flask-shaped, superficial or somewhat immersed, opening 
by single, central pores. 
About 20 species, widely distributed, especially in warm seas. 
The group of algee including this and related genera has been differently arranged 
by different authors and has recently been extensively divided. There is at present 
little uniformity in the treatment of the forms included in this group, and it seems prob- 
able that further work will change the arrangement proposed by present authors. 
Melobesia farinosa Lamouroux. 
Melobesia farinosa, Lamouroux, 1816, p. 315. 
Melobesia farinosa, Farlow, 1882, p. 180. 
Melobesia farinosa, De Toni, 1905, p. 1764. 
P. B.-A. Nos. 200, 1549. 
Frond forming small, thin, flat, more or less rounded disks, 1 to 5 mm. in diameter, surface fari- 
naceous, irregularly rimose from the center to the periphery, composed of a single stratum except in the 
vicinity of conceptacles; conceptacles scattered over the frond, o.1 to o.2 mm. in diameter, rather 
inconspicuous, opening by single central pores surrounded by elongated cells, but not conspicuously 
bordered by cilia. 
Generally distributed in all seas. 
Abundant on other alge on Bogue Beach, Beaufort, N. C., abundant on Sargassum filipendula 
dredged from coral reef offshore, July to August, 1915, probably at other times also. 
Forma callithamnioides (Falkenberg) Foslie. Fig. 47. 
Melobesia callithamnwoides, Falkenberg, 1879, p. 26s. 
Melobesia callithamnioides, De Toni, 1905, p. 1765. 
Melobesia farinosa {. callithamnioides, Foslie, 1905, p. 96. 
Fronds very variable, consisting of creeping, closely adherent, dichotomously branched filaments 
which are sometimes considerably elongated, often spreading out toward the apices and coalescent into 
more or less dense structures broken by more or less numerous interspaces, sometimes forming more or 
less complete dichotomously radiating disks, closely adherent by the entire lower surface; conceptacles 
of the same size as in the species, but rarer, the form being mostly sterile. 
Naples; Adriatic Sea. 
110307° 
