82 MARINE ALGA 
P. membranifolia. Several stems rise from same disk; branches 
expand into wedge-shaped, cleft or forked laminw; lobes bear on the 
summit other lamin or leaflets divided in the same manner. 
P. Brodici. Stem less branched and leaf-expansions broader and 
larger than in P. membranifolia; lamine wedge-shaped and deeply 
lobed. (Plate XIX.) 
Genus Sternogramme 
S. interrupta. Frond a thin membrane repeatedly forked, widely 
spreading, divisions one fourth to one half of an inch wide; fertile 
plants have the spores arranged in an interrupted line through the 
center of the segments resembling a midrib; frond two to eight inches 
high; bright red. It is found on the California coast. The illustration 
shows a plant on which the hydroid Sertularia pumila is growing. 
(Plate XIX.) 
GENUS Gymnogongrus 
G. Norvegicus. Frond two to four inches high, thin but leathery in 
substance, flat, narrow, divided in a regular forking manner; spreading 
ends of terminal forks obtuse; axils rounded; spores form spherical 
masses in the upper segments, and project on both sides like hemi- 
spheres. It resembles a simple form of Chondrus crispus, but is more 
delicate. The color is red or purple. This species is found in deep 
tide-pools from New York northward. (Plate XIX.) 
Genus Ahnfeldtia 
A. plicata. Frond coarse, stem-like filaments, stiff, wiry, irregularly 
and profusely branched; sometimes regularly forked and upper seg- 
ments equal; entangled; six to eight inches long; tufts several inches 
in diameter; dark purple or black. Specimens long exposed on the 
beach are faded to white. It is very common from New York north- 
ward, (Plate XIX.) 
Genus Callophyllis 
C. variegata. Deeply cleft, wide-spreading, flat, membranaceous 
frond; all parts notched more or less angularly; color dark to bright 
red; spores form hemispherical warts on surface. Some varieties differ 
from this one in having long and narrow, and others in having short 
and broad segments. It is a beautiful and common alga on the Pacific 
coast, resembling Euthora of the eastern coast. (Plate XX.) 
C. laciniata. Frond deeply cleft; segments wedge-shaped. It is 
found on the Pacific coast. (Plate XX.) 
Genus Irideca 
Frond rises from stalk and widens into a flat, thick, leathery, 
oval expansion, one to two feet long, and one to three inches broad ; 
