478 BULLETIN OF THE BUREAU OF FISHERIES. 
Antheridia and cystocarps have been described for one species of Actinococcus, but 
this observation seems founded on insufficient evidence. 
Actinococcus aggregatus Schmitz. 
Actinococcus aggregatus, Schmitz, 1893, p. 385, pl. 7, f. 8. 
Actinococcus aggregatus, De Toni, 1897, p. 259. 
P. B.-A. No. 786. 
Parasitic on Gymnogongrus griffithsie, the vegetative portion occurring as fine filaments between 
the cellsof the host; fruit appeating as a protuberant pad on the surface of the host, minute, about 1 mm, 
wide, rounded, flattened convex, single or several approximate; tetrasporangia cruciately divided, 
often imperfectly septate. 
North Atlantic and Pacific; Mediterranean Sea. 
On about one-fourth of the specimens of Gymnogongrus griffithsie, Fort Macon jetties, Beaufort N. C. 
Family 2. RHODOPHYLLIDACE Schmitz. 
Frond terte, flattened, or foliaceous, dichotomously or laterally branched; structure 
cellular or cellular-filamentous, seldom filamentous; tetrasporangia usually scattered 
over the thallus surface, sometimes collected into numerous sori, sunk in the outer 
cortex, which is often thickened to form nematheciumlike structures, nearly always 
zonately divided; antheridia usually in patches more or less widely distributed over the 
surface; carpogonia numerous on the fertile portions of the thallus, sometimes distant 
from the auxiliary cells and, after fertilization, fusing with one of these by a filament; 
auxiliary cells usually less numerous than the carpogonia, sometimes not formed until after 
fertilization; cystocarps scattered over the thallus, often situated at the edges, immersed 
or more or less prominent, usually provided with a conspicuous pore; gonimoblast 
suspended from an upper wall of the cystocarpic cavity, divided into several lobes 
radiating in all directions, forming spores in the apical cells of the filaments and some- 
times in the subapical ones also. 
About 110 species, all marine, in all parts of the world. 
KEY TO GENERA. 
a. Auxiliary cell forms on a protuberance bearing filamentous tufts, which radiate in every 
direction and ‘branch outward fasciculately:. o. 5. csiscevns xo oi nails eee mn aie sie re eae eaten b. 
b. Frond terete, radially branched, subtubular above, of cellular-filamentous structure 
se Pe Hates eis ory Cpe aethed oe os iows s+ frre Seat Ike Poe aeRO . 1. Agardhiella (p. 478). 
bb. Frond foliaceous, usually pinnately or furcately divided, with numerous warts or 
papille on the surface and margins. ................ 4.0 bees eee eens 2. Meristotheca (p. 479). 
aa. Auxiliary cell extends a thick projection into the cystocarpic cavity and bears at its apex 
TiiMIE GUS tif tS ofan ee ee ee ey eee ee nae tives te mats a stetetes shalt e-ooaelels js (mane c. 
c. Frond terete or slightly flattened, laxly tubular, sometimes caulescent and solid below 
apbde ees tema tants preter aed As A AEETEOSES - «Budiey sha-cd amines 3. Rhabdonia (p. 480). 
cc. Frond terete or flattened, structure dense, rigid, furnished with short, acute or obtuse, 
simpleior branched ipapilice:eiaacceriemteiieein dds ot (a. ls ciate kant 4. Eucheuma (p. 481). 
Genus 1. Agardhiella Schmitz. 
Agardhiclla, Schmitz, 1389, p. 441 (7). 
Frond terete, branched on all sides, subtubular and rather lax above, structure 
cellular-filamentous, medullary filaments reticulately anastomosing, more or less lax, 
cortex large celled within, very small celled without; tetrasporangia scattered over the 
surface, zonately divided; auxiliary cells not united with the carpogonia, scattered 
throughout the frond; cystocarps scattered through the frond, entirely immersed or 
