106 
DICTYOTACEiE. — Zonaria. 
IV. 
Boot clotlied witli entangled and curled woolly hairs, which extend a short way 
from the base, covering from half an inch to an inch square of the lower part of 
the frond. The frond, which eventually becomes a foot or more in length and 
divided nearly to the base into many narrow lobes, originates in a sessile or nearly 
sessile, broadly reniform, membranaceo-coriaceous lamina. This lamina has at 
first a circumscribed margin, forming a somewhat cycloidal curve, and is nearly 
undivided. When it attains an inch or two in height, vertical slits, commencing 
in the margin, extend downwards, dividing it in a pedate or palmate manner, into a 
great number of narrow, wedge-shaped lacunae, placed side by side in digitate order. 
These, as they grow, become flabellate above, from the divergence of the rows of 
cells of which they are composed, and are again cleft and re-cleft, until often the 
originally reniform leaf becomes a bunch of narrow ribbons growing from a central 
point. In all these changes the apical margin remains truncate, and circumscribed 
by a curved line. It is perfectly flat, not inrolled. Radiating strife, or inequalities 
in texture, proceeding from the base upwards towards each lobe, are more or less 
obvious in various specimens ; and faint concentric lines, paler than the rest of the 
frond, are seen here and there crossing the lobes, at distances of a quarter to half 
an inch. These are more evident on older and more divided specimens, though 
they occur on the upper or newer portions of their fronds. The radiating longitu- 
dinal bands or stria3 are sometimes very faint, and sometimes strongly marked. I 
have not seen fructification on any specimen collected at Sand Ivey A The colour 
when growing is a dark olive, reflecting prismatic colours, chiefly vivid greens and 
blues, from the striated surface. In fresh water a good deal of dark colouring 
matter is given out ; yet in drying the frond becomes exceedingly dark. In this 
state it adheres, but not very strongly, to paper, and shrinks very considerably. 
Not having seen authentically named specimens of Zonaria variegata , Ag., it 
would be rash to say that that species may be only an undeveloped or small state of 
the present. Some of my Sand Key specimens are so remarkably striated, or 
marked with darker and paler longitudinal bands, and others so obscurely banded, 
and there are such insensible gradations between the banded and unbanded 
individuals, that I fear a character derived from these bands will not stand good. 
If Z. variegata , then, be distinguishable from our Z. lobata , it will probably be by a 
character taken from the different form of the sori, which are said to be “ elliptical 
and scattered” in that species. 
Plate YII. C. Fig. 1 , plant of Zonaria lobata ; the natural size : fig. 2, small 
portion of the summit of a segment, magnified , to show the surface cellules. 
* The son, on West Indian specimens, form dark lines at both sides of the pale, concentric band ; 
but, besides these linear sori, others of irregular form are scattered between the bands. 
