136 TENTACLES OF ACTINIA. PAKT m. 



The European Caryophylliae never have more than one 

 star, but sometimes a great many individuals are united 

 in a spreading bunch, as in the madrepore Lobophylla 

 angulosa (fig. 130), or in a branched or tufted mass. 

 Their exterior is invariably striated, and each terminates 

 in a star, with the polypes, mouth and tentacles in its 

 centre. These compound madrepores are inhabitants of 

 warm seas. 



The number of tentacles possessed by the Actinian 

 polype varies with the species of the coral. When full 

 grown they have twelve, twenty-four, even forty-eight, 

 or more. When young, they have only four or six, but 

 in general the number increases rapidly as they advance 

 in age. The perpendicular hard lamellae, which divide 

 the cavity round the stomach of the polype into perpen- 

 dicular chambers, as in fig. 129, and form stars round the 

 mouth, consist of thin sheets or plates, either applied 

 or soldered together ; and for every new tentacle that is 

 produced at the mouth, a corresponding new chamber is 

 formed immediately below it, between the sheets or 

 leaves of the lamellae ; so that the number of chambers 

 and perpendicular plates is always equal to the number of 

 tentacles, and so the circulation of the fluids is main- 

 tained. Since the upper edges of the lamellae form the 

 rays of the stars round the mouth of the polype, it is clear 

 that the number of rays in a star must always be equal to 

 the number of lamellae. The new tentacles are always 

 produced exterior to and between the adjacent old ones, 

 so as to form an outer circle, and consequently a new 

 circle of rays will be added to the star round the mouth 

 exterior to the old ones. There may be two, three, or more 

 concentric circles of tentacles round the mouth of the 

 polype, the last being the shortest. However, some 

 polypes never have more than twelve tentacles during 

 the whole course of their lives. The first formed rays of 

 a star are generally, though not always, the longest and 



