COLLINS AND Howe: SPECIES OF HALYMENIA 171 
This species seems to be fairly common in Bermuda. Its 
favorite habitat is the walls of narrow deep clefts in the shore 
cliffs, such as are found between Tucker’s Town and Walsingham. 
Here it grows from a little below low-water mark down at least to 
a depth of two or three meters, usually as single separate plants 
rather than in dense tufts. It seems to thrive best where much 
shaded. In an unattached condition it occurs also among man- 
grove roots, as in the vicinity of Hamilton. These loose fronds are 
darker in color, firmer in texture, and less adherent to paper when 
dried under pressure than are the attached forms. There is much 
variation in the form of the frond; the primary form seems to be 
orbicular and plane with a slightly developed stipe. Rapid marginal . 
growth of the frond results in ruffles and plications, and when these 
are well developed the plant has somewhat the aspect of Porphyra 
amplissima in miniature. In color and habit it is often suggestive 
also of certain conditions of Callymenia reniformis, from which, 
however, it differs markedly in structure. Proliferous growth is - 
common; the proliferations are sometimes sessile but are oftener 
stipitate, the stipe terete or flattened, in the latter case with or 
without an obvious costa, which may be continued into the base 
of the main expansion. In the older ‘plants, under certain con- 
ditions of growth, the basal stipe, terete or flattened, may branch 
and form a matted subrhizomatous complex from which individual 
fronds arise, these usually orbicular or cuneate, or sometimes 
cordate from a cuneate base. An important character of this 
Species is the presence, in the medulla, of conspicuous stellate 
ganglia more or less similar to those exhibited by the type speci- 
men of Halymenia floridana J. Ag. and by Sebdenia heteronema 
M. A. Howe.* These may be easily observed through the cortex 
by transmitted reduced light under low-power lenses without the 
use of any staining reagents; however, their protoplasts have ° 
Peculiar affinity for haematoxylin stains and they may be differ- 
entiated with remarkable distinctness by overstaining with prepar- 
ations of haematoxylin and afterwards partly decolorizing. The 
nodes of the ganglia are irregularly stellate or subglobose ; from each 
of them radiate three to ten coarse rather rigid and straight a. 
ing filaments with dense homogeneous refringent contents; 1 the 
* Mem. Torrey Club 15: 163-165. pl. 58. 1914- 
