148 Froceedinr/s of the Royal Physical Society. 
, I have received only a minute portion, without vesicles. 
Bay of San Francisco. 
3. Sertularia corniculata, Murr. Plate VI. fior. 3. 
Cells not quite opposite, sometimes nearly alternate, form- 
ing an open cup resting on the stem ; lip not distinct ; exterior 
margin somewhat projecting at tip ; a single one in the axilla 
of each pinna. Vesicles pear-shaped, with two long points 
projecting like horns at the thick end ; aperture between them. 
This is a very elegant little species, and is easily distin- 
guished by the two long horns at the top of the vesicles, which 
remind one somewhat of a fool's-cap, and by the wholly open 
cells. 
Bay of San Francisco. 
4. Flnmularia gracilis, Murr. Plate VII. fig. 1. 
Stem slightly flexuose, branched; branches alternately pin- 
nated ; cells ranked closely in twos and threes ; tubulous, with 
a plain ym slightly peaked in front ; vesicles oblong-oval. 
The characters of this Flumularia do not differ greatly from 
those of P. falcata ; but its habit is so different that it can 
scarcely be mistaken for it. The branches are closer, and 
more thickly set, than in F. falcata ; their arched disposition 
is wanting ; and the whole plant has more the aspect of a Ser- 
tularia than a Flumularia. The cells are proportionally 
larger than in F. falcata ; instead of a plain truncate rim, 
it has one slightly peaked in front, or excised at the sides. 
Each cell has also a sort of support, like a triangular buttress, 
below it, marked or lined off from the cell itself. 
Bay of San Francisco. 
5. Flumularia struthionides, Murr. Plate V^TI. fig. 2. 
Shoots simple, plumous, the pinnse alternate ; cells close, 
each occupying the whole of one side of the joint to which it 
is attached, cup-shaped, wdth a toothed margin, of which the 
teeth are unequal, the one in front projecting much more than 
the rest ; vesicles gibbous, girt with toothed ribs. 
This species is nearly allied to P. eristata, but is much 
closer in habit, both the pinnse and the cells being nearer each 
