102 
DICT Y OTACEiE. — Haliseris. 
iv. 
ff Frond linear , dichotomous. 
Y. Dictyota. 
ff Frond undivided. 
VIII. PUNCTARIA. 
IX. Soe anther a, Post, and Rupr. (I do not see how this differs from Punctaria .) 
* * * Frond cylindrical , or hag-like. 
-j- Branched. 
VI. Stilophora. Seri wart-like, composed of spores and moniliform threads. 
VII. Dictyo siphon. Spores either solitary and scattered, or collected into dot-like 
sori. 
ft Unbranched , hag-like. 
X. Asperococcus. 
**** Frond pierced with round holes , lace-like. 
XL Hydroclati-irus. 
1. HALISERIS. Tozzetti. 
Root coated with woolly hairs. Frond flat, linear, membranaceous, traversed by 
a cartilaginous midrib. Spores collected in naked sori , disposed in longitudinal 
lines at either side of the midrib, and rising from both surfaces of the membra- 
nous frond. Paranemata forming groups separate from the sporiferous sori. 
This is the only genus in the Order in which the frond is traversed by a midrib ; 
and one species (H. Areschougia , J. Ag.) is described as being nerveless. In most 
species the membranous border of the frond tears with ease in an oblique direction 
toward the midrib ; so that it is rare to find specimens of full size in which the 
lower part of the fronds is not much jagged. The margin is either entire, or 
minutely denticulate, and is sometimes thicker than the rest of the membrane. In 
two species the midrib throws off lateral secondary nerves which traverse the 
frond toward the margin, ascending obliquely. Of the ten species known, four are 
American, four South African, one Australian and Indian, and one a native of the 
tropical and temperate regions of the Eastern Hemisphere. The name, derived 
a\s and crept s, is spelled Halyseris by Agardh, &c. 
