510 HowE: PHYCOLOGICAL STUDIES 
irregularly perforate, the margins entire or sinuate or here and 
there irregularly dentate or lacerate, the surface nitent, the color 
mostly a light greenish rose; medullary filaments sparingly lat- 
erally or subdichotomously branched, 14-24u in diameter, gradu- 
_ ally enlarging distally (often becoming 27—40y in older parts) and 
each terminated by a subglobose capituliform cell, this 45-95 
in diameter and emitting radially or stellately 3-14 (usually 6 or 
7) rather straight and rigid branches, these connecting with one 
or two series of similar or more flattened radiately branched and 
reticulately joined subcortical cells, succeeded by one or two series 
of smaller subglobose or flattened anastomosing subcortical cells 
and the monostromatic or occasionally distromatic cortex; the 
cortical cells subglobose, obovoid, or more often flattened in the 
plane of the surface, 5-13 in diameter, usually 3-6 from each 
subjacent cell: other parts unknown. [PLATE 34.] 
La Paz, Vives 20d. 
The three specimens on which the foregoing description is 
based are evidently fragments and some of the details of the 
diagnosis, especially as regards the size and form of the thallus, 
may require modification when more material is available. The 
specimens, also, appear to be sterile, but their structural characters 
are such that we feel little hesitation in referring them to the 
Hymenopsis section of Halymenia—the section that includes the 
European and Mediterranean Halymenia latifolia Crouan and H. 
ulvoidea Zanard., and possibly also the American H. floridana J. 
Ag. Halymenia latifolia has a firmer, relatively narrower, less 
nitent thallus of more definite regular form and a well-defined 
cuneate stipe; it is not certain that the holdfast is present in any 
of the Baja California fragments, but what appears to be a sub- 
truncate or slightly cordate base in one of them suggests that the 
plant is sessile. H. latifolia has radially branched cells in the 
subcortex that sometimes resemble the smaller of the radiate or 
stellate subcortical cells of H. actinophysa, but they are (in a Brest 
specimen) only 25—30y in diameter, have usually but 3-5 branches, 
and are nearly always much flattened; if these radiate cells in H. 
latifolia often in form suggest Asteroid or Ophiuroid “star-fishes,”’ 
the corresponding cells in H. actinophysa in a detached condition 
may remind one of the pollen grains of certain Malvaceae or the 
“‘morning-star’’ maces of the 15th century. 
The limits of Halymenia floridana J. Ag. are imperfectly under- 
