96 



CELTIC PROVINCE. 



{Trochus umbilicatus), and towards the south with 

 the larger Trochus crassus. Here are sea-anemones, 

 especially Actinea mesembryanthemum, like masses 

 of brilliant crimson or bright green pulp, but when 

 covered by the water, expanding into many-armed 

 disks, and displaying shapes and colours of exquisite 

 beauty. A fourth sub-region succeeds, the lowest 

 belt above low-water mark, distinguished by the 

 presence of Fucus serratus, the saw-toothed shining 

 black sea-weed, so much used in the packing of 

 lobsters for market. It takes the place of Fucus 

 articulatus. On its fronds creeps the lowermost in 

 succession of the periwinkles, the variously tinted 

 Littorina neritoides, exhibiting every colour in its 

 obtuse and thickened shell, pure yellow, bright red, 

 rich brown, dark olive, and all possible changes of 

 striping and mottling. With it is associated every- 

 where Trochus cinerarius, except, and this exception 

 applies generally to all the creatures whether ani- 

 mal or vegetable, where the coast is composed en- 

 tirely of fine sand or clean gravel. 



At the verge of low-water mark, immediately 

 below it, wherever the coast is rocky, there are all 

 round the British shores, within a space of a few 

 inches, a remarkable series of more or less distinctly 

 defined belts, each consisting of a different species 

 of seaweed. These, in succession, are the Laurencia 

 pinnatifida, uppermost ; then the green Conferva 

 rupe.stris ; then the elegant and firm, often iri- 

 descent fronds of Chondrus crispus ; and, lowermost, 



