Plate XVIII. 



Fig. 75. MYRIONEMA CLAVATUM. 



Colour. "Nearly the colour," says Captain Carmichael, "of the then purplish crust 

 on which it grows." 



Character of Frond. "Very minute; rather convex," the threads {filaments) oi whiah. 



it is composed, club-like ("clavate"); mostly cleft in two ("bifid"). 

 Measurement. The description does not specify. 

 Fructification. Minute seeds (spores) affixed to the filaments. 

 Habitat. Not defined. 



Nothing is known of this plant beyond Captain Carmlchael's description and 

 figure, and the account is very imperfect. For the other Myrionemas, refer 

 back to Plate XVI. Figs. 68, 69, 70. 



Fig. 76. SPHACELAEIA SERTULAEIA. 



Colour. Olive-green. 

 Substance. Higid; but delicate. 



Character of Frond. Delicately bushy. Stem and branches jointed throughout; 



thread-like {filiform). Stem slightly shaggy at base; weak and slender; 



irregularly branched. Branches alternate; spreading horizontally; two or three 



times re-branched. Angles of branching very wide. 

 Measurement. Scarcely 3 inches long. 



Fructification. Oval seeds {spores) borne on the branchlets. 



Habitat. From deep water. South of England, and North and West of Ireland. 

 Very rare. 



A smaller and slenderer plant than S. fiUcina, but Dr. Harvey hesitates about 

 making two species of them. S- filicina has, however, all its angles of branching 

 very acute and narrow; while those of S. sertida.ria are very obtuse and wide; 

 the branching of S. filicina is therefore erect, that of S. sertularia spreading. 



Fig. 77. SPHACELARIA CIKRHOSA. 



Colour. Dark-brown; or rusty. 

 Substance. Rigid; yet not coarse. 



Character of Frond. A star-like tuft, more or less dense, growing on the stems of 

 other algse. Jointed throughout ; thread-like {filiform)-, assuming many forms. 

 Each thread {filament) of the tuft, branched with short, olten (but not 

 always) opposite branchlets. There are many deviations, and the branching 

 is more or less complicated, but S. cirrhosa is always a tift. 



Measurement. An inch or more long; often less. 



Fructification. Griobose seeds {spores) borne on the branchlets. 



Habitat. Our coasts everywhere. On Halidrys siliq^uosa abundant; and common on 

 numerous other plants. 



A very dwarf variety has been observed by Miss Cutler, on the stems of 

 Desmareiitia aculeata. 



35 



