90 DIVERSIONS OF A NATURALIST 



which secrete it, but takes the form of a supporting 

 central or axial rod (sea-pens), or branched tree (sea- 

 bushes), upon which the fleshy mass of polyps are 

 tightly set. This is the case with the precious red and 

 pink coral of the Mediterranean (which is now being 

 " undersold " actually in the Mediterranean markets by 

 a similar red coral from Japan, usually offered as the 

 genuine article, which it is not !). 



On the British coast you do not, as a rule, find 

 coral-forming polyps. A small kind, consisting of two 

 or three yellow and orange-red anemone-polyps united 

 and producing a small group of hard calcite cups 

 (Caryophyllia and Balanophyllia) is not uncommon at 

 Plymouth at a few fathoms depth. But you have to go 

 to the Norwegian fiords or else far out to sea where you 

 have 300 fathoms of sea-water in order to get really 

 luxuriant white corals — the beautiful Lophohelia (Fig. 3, 

 p. 9), which I used to dredge in the Nord Fiord near 

 Stavanger, as branching, shrub-like masses of a foot cube 

 in area, each white marble cup standing out from the 

 stem, an inch long and two-thirds of an inch across, and 

 the stems giving support to a whole host of clinging 

 growths (among them Rhabdopleura !) and sheltering 

 wonderful deep-water worms and starfish. 



But these, beautiful as they are, are nothing, so far 

 as mass and dominating vigour of growth are concerned, 

 in comparison with the reef-building corals of the warm 

 seas of the tropics. There these lime-secreting con- 

 glomerated sea-anemones separate annually hundreds of 

 tons of solid calcite per square mile of sea bottom from 

 the sea-water, and build up reefs, islands, and huge 

 cliffs of coral rock. They get the calcite — as do 

 calcareous seaweeds and shell-making clams, oysters, 



