74 
LIFE, IN 1X8 LOWER FORMS. 
film of gelatinous flesh, so tightly stretched as to be 
reduced to an invisible tenuity. 
In these massive or arborescent Corals, each single pit 
must be considered as the habitation of a single animal ; 
and the whole body bears the same relation to the little 
simple Madrepores of the European seas, as the compound 
Laomedea , with its numerous branches and cells, bears to 
the solitary Hydra. The elegant Coral that studs the 
rocks of Devonshire and Cornwall ( Cyathina Smithif) is an 
instructive example of the simple species. It consists of 
a stony cylinder or inverted cone, the summit of which, 
hollowed into a shallow cup, is formed by the edges of 
thin plates that radiate towards the centre. While in its 
native element, a pellucid gelatinous flesh emerges from 
between the plates, sometimes rising to the height of an 
inch above their level ; exquisitely formed and coloured 
tentacles fringe the sides of the cup-shaped cavity, across 
which stretches the oral disk, marked with a star of some 
rich and brilliant colour surrounding the central mouth, 
— a slit with white crenated lips, like the orifice of one of 
those elegant cowry-shells that we put upon our mantel- 
pieces. 
In this condition the affinity between a Madrepore and 
an Actinia is seen to be very close. Indeed, if we imagine 
calcareous particles to be deposited on the surfaces of 
the radiating membranous partitions of the latter, we 
should have the stony plates, and the Actinia would be in 
every essential point turned into a Coral. The habits 
and economy of the two forms coincide exactly, except 
that the Madrepore is permanently attached to the rock 
by the adhosion of its stony skeleton, while the attach- 
