148 HALYMENIA GINANNIA. 



stem. In others there is scarcely any stem, but 4 or 5 branches rise from 

 a point near the root, and these are 10 or 12 inches long and an inch in 

 diameter. Other varieties are but two or three inches high, both stem and 

 branches filiform. /3. is remarkable for compressed stems, from half an 

 inch to an inch wide, crisped and curled. Conceptacular fruit or favellce 

 abundantly scattered over the whole frond, giving it a dotted appearance. 

 I have never seen the tetraspores. 



XI. HALYMENIA. Ag. [Plate 19, D.] 



Frond compressed or flat, gelatinoso-membranaceous, con- 

 sisting of a double membrane, separated by a very lax net- 

 work of articulated filaments ; cells of the membrane minute, 

 coloured. Fructification : spherical masses of spores (favel- 

 lidia) immersed in the frond, attached to the inner surface 

 of the membranous periphery. Name, from Xf, the sea, and 

 vwv, a membrane. 



1. H. ligulata, Woodw. ; frond compressed or flat, irre- 

 gularly dichotomous or palmate, the segments attenuated, 

 often proliferous at the margin. Grev. Alg. Brit. p. 162, t. 

 17; Hook. Br. Fl. ii. p. 308; Wyatt,Alg. Danm. No. 125; 

 Harv. Phyc. Brit. t. cxii. Ulva ligulata, E. Bot. t. 429. 



On rocks and stones in the sea, chiefly along the southern shores of 

 England and Ireland. Annual. Summer. Frond extremely variable in 

 form and ramification, and in substance, but resolvable into three principal 

 varieties. 1, dichotoma ; frond 6 8 inches long, half a line to 1 or 2 lines 

 broad, compressed, very gelatinous, many times divided in an irregularly 

 dichotomous manner, the divisions nearly of equal breadth, becoming gra- 

 dually narrower towards the extremities, which are tapering and acuminate. 

 2, ramentacea ; frond 12 14 inches long, compressed, divided into three 

 or four principal lobes or branches, from half an inch to an inch in breadth, 

 and from 1 4 inches long, attenuated at base, thence cylindrical till near 

 the apex, when they again slightly taper. In substance this closely resem- 

 bles the first variety, containing a great quantity of gelatine, the external 

 membrane being very thin, and of a pale rose-colour. 3, latifolia ; frond 

 12 20 inches long, 2 4 inches wide in the widest part, rising from a mi- 

 nute stem, wedge-form, either simple or forked, or once or twice irregularly 

 cleft in a palmate manner, the segments 1 or 2 inches broad, destitute of 

 ramuli ; of a dark red colour, and soft, but not very gelatinous substance 

 (very similar in feel to Rhodyrnenia reniformis), perfectly flat, the stratum 

 of gelatine interposed between the membranes being very thin. The fruc- 

 tification is abundantly scattered over every part of the frond, and, to the 

 naked eye, resembles minute dark red dots. 



XII. GINANNIA. Mont. [Plate 19, C.J 



Frond terete, dichotomous, membranaceo-gelatinous, tra- 

 versed by a fibrous axis, from which slender, dichotomous, 



