Fig. 364. CALOTHRIX SEMIPLENA. 



Colour. Verdigris green. 

 Substance. Rigid. 



Character of Frond. Tufts of very slender, wavy threads ( filaments) ; densely inter- 

 woven into compressed bundles. Filaments unbranched; tubular; containing 

 narrow, cylindrical colour-cells; some of which are apt to run out, leaving 

 empty transparent patches in the tubes; the rest showing through, with 

 division -lines. 



Measurement. One or 2 inches high. 



Fructification. As before. 



Habitat. Our coasts generally. In rock-pools near high-water mark, growing on 

 CoralUna officinalis and other small algae. 



Fig. 365. CALOTHRIX HYDNOIDES. 



Colour. Dark olive-green (blackish under the microscope). 

 Substance. Eigid; plush-like, not velvety. 



Character of Frond. Slender, wavy, obtuse threads {filaments^ ; some interwoven 

 into a thin, flat layer; others rising up in close, stiff, sharp-pointed tufts; 

 forming thin patches. Filaments not branched, but lying against each other 

 as if they were; especially above, where three or four crowd together, co- 

 hering by their ends, and bristhng out in sharp points; tubular; containing 

 narrow, cylindrical black-green colour-cells, which show through, with division- 

 lines. 



Measurement. Filaments an inch hio-h. Patches, an inch or two across, on the 



clayey shore. Spreading for several feet on rocks. 

 Fructification. As before. 



Hahitat. Appin. On the clayey sea-shore near high-v/ater mark. 



Much more rigid and harsh-feeling than C scopulorujn, and very like pieces 

 of rough i^lusli. Known from G. pannosa by much shorter filaments, and the 

 sharp tooth-like tops of the tuft-divisions. 



Fig. 366. CALOTHRIX C^SPITULA. 



Colour. Blackish green. 

 Substance. Soft; velvety. 



Character of Frond. Close, very round, cushion-like tufts of densely-packed threads 



(^filaments). Filaments upright, wavy, blunt, often twisted into small bundles; 



not branched, but sometimes lying against each other as if they were; 



tubular; containing very narrow, cylindrical colour-cells, which show through; 



their division-lines very strongly marked. 

 Measurement. Tufts from J to Ij inch in diameter. 

 Fructification. As before. 



Habitat. Spanish Point at Miltown Malbay, Co. Clare. In rock-pools near high- 

 water mark. Only once found in Ireland. 



80 



