372 THE INHABITANTS OF THE SEA. 
shrubberies; and frequently the gigantic tridacna, embedded in 
their calcareous parterres, discloses, on opening her ponderous 
valves, her violet mantle tinted with emerald-green. The en- 
chanted naturalist lingers for hours over the magnificent spec- 
tacle, and forgets the lapse of time, as wonders upon wonders 
c1owd on his enraptured gaze. 
But the tropical coral-gardens serve not only as a harbour of 
refuge to the numberless creatures that frequent their laby- 
rinthine recesses, for many annelides, crustaceans, asterias, and 
even fishes, feed upon their animal flowrets. Among these, 
the Scari are provided with a very remarkable dental apparatus 
to protect their mandibles from injury while biting the cal- 
careous corals. These fishes have their jaws, which resemble 
the beak of a parrot (whence they receive their usual appellation 
‘* parrot fishes”), covered externally with a kind of pavement of 
teeth, answering the same purpose as the horny investment of 
the mandibles of the bird. The teeth that form this pavement 
are perpetually in progress of development towards the base of 
the jaw, whence they advance forward, when completed, to 
replace those which become worn away in front by the constant 
attrition to which they are subjected. Thus armed, the Scari 
browse without difficulty on the newest layers of the stony 
corals, digesting the animal matter therein contained, and 
setting free the carbonate of lime in a chalky state. Many of 
the Diodons, Cheetodons, and Baliste or file-fishes, of which 
Kittlitz saw some new species, one still more splendid than the 
other, in every lagoon-island he visited in the long range of 
the Carolines, likewise feed upon corals, and possess a dental 
apparatus fit for masticating their refractory aliment. The 
Diodons have grooved teeth, excellently adapted to crush and 
bruise, and the Baliste have eight strong conical teeth in every 
jaw, with which they easily nip off the shoots of the coral bushes. 
Of the reef-building corals it may well be said that they 
build for eternity. The bones of the higher animals vanish 
after a few years, but the stony skeleton of the polyp 
remains attached to the spot of its formation, and serves 
as a basement or stage for new generations to build upon. 
Life and death are here in concurrent or parallel progress ; 
generally the whole interior of a corallum is dead. The 
large domes of the astraeas are in most species covered 
