Fig. 253. GEIFFITHSIA SETACEA. 



Colour. A bright transparent crimson ; which is given out very soon in fresh water. 

 Substance. Remarkably crisp and firm when fresh ; soon becoming flabby and soft 

 on exposure. 



Character of Frond. Tufts of distinctly marked, jointed threads {filaments), forming 

 a more or less rounded outline. Filaments as thick as hogs' bristles; very 

 straight; irregularly forked; angles of branching {axils) narrow; lesser branches 

 sometimes opposite; occasionally throwing out below a few root-like fibres, 

 which connect the filaments together. 



Measurement. From 3 to 6 inches long. 



Fructification. Of two kinds. Minute sjpores in stalked, mostly double, capsules; 



surrounded by enfolding branchletm^s. 2. Tetraspores crowded on the inner 



sides of special enfolding branchletm^s. 

 Habitat. Our shores generally. On rocks, &c. between tide-marks under the shade 



of large algae. Common. 



Fig. 254. CALLITHAMNION PLUMULA. 



Colour. A beautiful rose-red. 

 Substance. Delicately soft and tender. 



Character of Frond. Tufts of jointed threads {filaments) very much branched. Stems 

 undivided or somewhat forked; furnished with alternate or irregular slender 

 branches; the upper ones longest and most divided; all the divisions and 

 branches at one level (distichous); every joint bearing a pair of short, hori- 

 zontal, or back-curved, exactly opposite branchlets, whose upper margin is 

 clothed with a second set; these sometimes with a third; all regularly set 

 like the teeth of small combs {ijcctinated). 



Joints. Visible throughout (when examined through the microscope). 



Measurement. From 2 to 5 inches long. 



Fructification. Of two kinds. 1. Minute spores in large, dark-red, double capsules; 



sessile on the main branches. 2. Minute, globose tetraspores borne on the 



tips of the then shortened branchletee;^s. 

 Habitat. Our coasts from Orkney to Devon, but in the warmer stations. Dublin, 



&c. On rocks, &c. near low-water mark. Not uncommon. 



Fig. 255. CALLITHAMNION CRUCIATUM. 



Colour. A brownish-red; soon fading to yellowish. 

 Substance. Soft and fiaccid (limp). 



Character ofi Frond. Dense tufts of jointed threads {fidaments)-, branched, but 

 rather sparingly. Stems irregularly divided into, or furnished with, a number 

 of long, almost simple branches, which are sometimes rebranched. Each joint 

 throughout, clothed with one or sometimes two pairs of slender, upright, some- 

 times simple, oftener re-branched, brallchlet^<??^5. These so crowded at the tips 

 that they present a darkened appearance, like the eye in a peacock's tail. 



Joints. Visible throughout (under the microscope). 



Measurement. From 1 to 2 inches long. 



Fructification. Only one kind known. Tetraspores, dark-red, sessile on the (then) 



shortened branchlet<?^7zs. 

 Habitat. South of England and south and west of Ireland. On mud-covered rocks 

 near low-water mark. Kare. 



36 



