IV. 
DICTYOTACEvE.— Dictyota. 
Ill 
laciniie spreading, especially the upper ones ; apices divaricate, the younger ones 
sharply bifid, each lobe acuminate ; spores forming minute sori scattered over the 
whole surface of the lamina. — J. Ag. Sp. Alg. vol. 1 , p. 94. Kiitz. Sp. Alg p. 554. 
(Tab. YIII. C.) 
ITab. Tropical. Coast of Mexico, at Yera Cruz, Liebman ! (v. s. in Herb. 
T.C.D.). 
Frond three or four inches long, one or two lines in diameter, of nearly equal 
breadth throughout, many times dichotomously divided, with rounded axils and 
spreading segments. The uppermost divisions are more or less divaricated. The 
margin is entire and flat. The young apices are sharply notched or bifid ; each 
notch deltoid-acuminate, ending in a sharp point. The sori are minute and 
densely dotted over the whole surface. In our specimen they have fallen away, 
leaving cavities in their place. The substance of the frond is thickish, somewhat 
coriaceous, and the structure is denser than in some other species. The surface 
cellules are minute ; the areolations beneath them not much longer than their 
breadth. In drying, this plant does not adhere to paper. Known by its sharply 
bifid apices from any state of D, fasciola or D. dichotoma. Distinguished from 
D. acutiloba by the widely scattered fructification. 
Plate YIII. C. Fig. 1 , Plant of Dictyota Bartayresiana ; the natural size ; fig. 
2, apex of a segment, magnified ; fig. 3, extremity of the same, with depressions from 
which sori have fallen, and showing the surface cellules and internal cells ; highly 
magnified. 
5. Dictyota cremdata , J. Ag. ; frond woolly at the base, repeatedly dichotomous, 
coriaceo-membranaceous, with patent, but not very blunt axils ; laciniaa linear, 
undulate; the margin eroso-dentate, the toothlets close together and of unequal 
size ; apices very blunt, lingulate ; sori at length occupying the whole surface. 
J. Ag. Sg>. Alg. vol. 1 ,p. 94. Kiitz. Sp. Alg. p. 558. 
TIab. Tropical. At St. Augustin, on the Pacific coast of the Mexican Republic, 
Liebman ! (v. s. in Herb. T. C. D.). 
Fronds tufted, 2 — 4 inches high, about one and half or two lines in breadth, gra- 
dually Avider from the base upwards, many times closely dichotomous ; the segments 
spreading, the Avhole frond having a fan-like outline. The sinuses betwen the lacinise 
are rounded, though not conspicuously so, and the upper ones are rather narrow. The 
margin is undulated, and closely eroso-denticulate, or jagged with unequal, deltoid, or 
subulate, tooth-like processes. The apices are rather Avider than the portions beloAv 
them, and so blunt as to be almost truncate. The young ones are obtusely emar- 
ginate. The sori are small, at first forming patches here and there, but eventually 
