Seu. aONGYLOSrErvME.E. ( 60 ) Fam. CRYrTONEMIACEyE 



Plate XCIL a,b, 

 HALYMENIA LIGULATA.— ^^7. 



Gen. Char. — Frond gelatinoso-membranaceous, flat or compressed, composed of a douhk 

 membrane of very minute coloured cells, separated by an extremely lax network of 

 jointed fibres. Fructification, consisting of favellidia attached to the inner surface 

 of the membrane. Name from aAy, " the sea, " and ujuijj/, "a membrane." 



Halymenia ligulata. — Frond shortly stipitate, flat, or in the narrow 

 varieties compressed, irregularly dichotomons, often proliferous from the 

 disc and margin. 



'&■ 



Halymenia Ii(/idata. — A;j. Sp. Alg. vol. i. p. 210; Ag. Syst. p. 244; Spreng . Syst . 

 Veg. vol. iv. p. 333; Grev. Alg. Brit. p. 162, t. 17; Hooh. Br. Fl. 

 vol. ii. p. 308 ; Wyatt, Alg. Damn. No. 425 ; Endl. 3rd Suppl. p. 40 ; 

 Harv. in Mach. Fl. Hib. part 3, p. 188 ; Harv. Man. p. 148 ; Harv. 

 Syn. p. 122 ; Atlas, plate 48, fig. 216 ; /. G. AgardJi, Sp. Gen. Alg. 

 vol. ii. p. 201. 



Halymenia elongafa. — Ag. (S^. Alg. vol. i. p. 209; Ag. Syst, p. 243; J. Ag. Mcdit. 

 p. 98. 



Halaeachnion ligulatvm. — Kiitz. Phyc. Gen. p. 394, t. 74, f. 1. 



Ulva ligidata. — Woodu: in Linn. Trans, vol. iii. p. 54; E. Bot. t, 420. 



Ulva rubra.— Huds. Fl. Angl. p. 571 ; E. Bot. t. 1627. 



Mesogloia Hudsoni. — Ag. Syst. p. 50 (not of British authors). 



Hab. — On rocks, stones, and old shells near low- water mark ; oftener to be found in 

 four to twelve fathoms water. Annual. Summer. Not unfrequent on the southern 

 shores of England, east, south, and west coasts of Ireland ; scarcer in Scotland, but not 

 uncommon on the Ayrshire coast [Rev. Dr. Landsborovgh) ; Peterhead {Mr. T. Bell) ; 

 Jersey, very common. 



Geogr. Dist. — Atlantic shores of Europe ; Mediterranean Sea, 



Description. — Root, a very small conical disc. Stem short, a quarter 

 of an inch to one inch long, cylindrical, becoming gradually compressed, 

 and in the broad varieties flattened into a once or twice or many times 

 iiTegularly dichotomous frond, six to ten or even twenty inches in length ; 

 the segments from one-eighth to two inches or more in width, with 

 rather nari'ow but rounded axils, the disc and margin often beset with 

 proliferous elongations, which are generally snjall and simple, but occa- 

 sionally elongated, once or twice divided, acute at the points and 

 attenuated towards the base, sometimes again giving rise to minute 

 processes. Occasionally the branches are regularly dichotomous, but 



