Fig. 193. GRACILARIA COMPRESSA. 



Colour. A transparent dull red; becoming brigliter in fresh water. 



Substance. Very tender and brittle; succulent; somewhat gelatinous. 



Character of Frond. Tufts of cylindrical,, or somewhat compressed stems, 

 which are either undivided and alternately branched from the base, 

 or partly forked at first; alternately branched afterwards. Branches 

 long, and mostly simple; tapering to a fine point; occasionally furnished 

 with branchlets. 



Measnrement. From 6 to 12 inches long. 



Fructification. Of two kinds. 1. A mass of spores in almost conical cap- 

 sules; external; sessile on the branches. 2. Tetraspores minute; 

 imbedded in the same. 



Hahitat. South of England. Cast ashore from deep water. Very rare. 



Fig. 194. GIGARTINA MAMILLOSA. 



Colour. A dark purple. 

 Suhstance. Gristly; tough; elastic. 



Character of Frond. Tufts of, first cylindrical, then flat stems, becoming 

 channelled or grooved upwards, and widening into wedge-shaped, 

 irregularly forked {dicliotomous) divisions, or branches. Divisions 

 channelled; more or less broadly wedge-shaped; often forked at the 

 tips; the angles acute; their surface and margins dotted over with 

 minute, short, thick, stalked frondlets, in which the capsular fruit is 

 formed. 



Aleasurement. From 3 to 6 inches high. Width of the divisions varying 

 greatly in difierent specimens. 



Frmtification. Only one kind observed. A mass of spores in globose cap- 

 sules; formed on the frondlets. 



Habitat. Our coasts generally. On rocks, &c. .near low- water mark. 

 Common. 



For other Giqartinas see Plate XLITI. Fig. 197; Plate XLIV. Fig. 201; and 

 Plate L. Fig. 225. 



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