36 



POLYPIFERA. 



early state, when the radiating plates are first 

 developed. At this time their upper discs 

 are scarcely larger than the stem, but they 

 soon begin to spread, and show indications of 

 their characteristic form. There are many 

 instances of smaller individuals remaining 

 fixed to large ones in a living state, and such 

 specimens are not unfrequent in collections 

 of corals. But in all cases that I have seen, 

 the younger ones are attached to the under 

 side of the old one, and I believe them to be 

 cases of accidental attachment." 



"In Ellis's Zoophytes (p. 146) is the fol- 

 lowing passage, quoted from Rumphius, in 

 regard to the animal of F. agariciforinis. * The 

 more elevated folds or plaits have borders 

 like the denticulated edge of needlework lace; 

 these are covered with innumerable oblong 

 vesicles, formed of a gelatinous substance, 

 which appear alive under water, and may be 

 observed to move like an insect.' 1 have ob- 

 served these radiating folds of the animal, which 

 secrete the lamellae, and which shrink between 

 them when the animal contracts itself on being 

 disturbed. They are constantly moving in tre- 

 mulous undulations, but the vesicles appeared 

 to me to be air vessels placed along the edges 

 of the folds ; and the vesicles disappeared 

 when the animal was touched." 



" This arrangement of air vessels would very 

 materially assist in keeping uppermost the 

 convex disc of the coral, and be of vital im- 

 portance to the young polype at the time of 

 separation, and subsequently in keeping it 

 upon the surface of its sandy bed ; or if they 

 were moved by a sudden roll of the sea, 

 which would lift even the most ponderous 

 and possibly convey them a considerable dis- 

 tance, they would be again deposited in their 

 natural position. That they have no power of 

 turning themselves I proved, during a sojourn 

 of six weeks at Tahiti, by placing a healthy 

 specimen with its upper surface downwards, 

 during which time it remained in the position 

 placed, and the vitality of the points of con- 

 tact with the rock upon which it was laid 

 was destroyed. In Fungia limacina I have 

 seen instances where the coral, having been 

 accidentally placed and permanently fixed in 

 such unusual positions, has adapted itself to 

 its new situation, by increasing upon its edges, 

 and forming a new convex surface." 



" As long as the young Fungia retains the 

 form of a Caryophyllia, it is entirely enveloped 

 by the soft parts of the animal ; but as the 

 upper disc of the coral spreads and it assumes 

 its characteristic form, the pedicle is left 

 naked, and the soft part extends only to the 

 line where the separation afterwards takes 

 place." 



" I consider the cases in which young Fungiae 

 are found fixed to the under side of others of 

 the same species to arise from the accidental 

 attachment of the young polype when de- 

 tached from its parent, and by the motion of 

 the water floated underneath a larger one of 

 its own species, the edges of which were not 

 so even as to touch the rock or coral on 

 which it rested at every part of its surface. 



In such cases the soft parts of the older spe- 

 cimen would continue to cover the short stem 

 of the younger individual, and hence its se- 

 paration from its pedicle would be prevented." 



The genus PolyphyUia is, in its essential 

 structure, closely allied to the Fungiae described 

 above, but the upper surface of its stony poly- 

 pary, instead of being furnished with lamellae, all 

 diverging from the same centre, is covered with 

 numerous smaller laminae, diverging from differ- 

 ent centres, but generally arranged perpendicu- 

 larly to the long axis of the polypary. In the 

 living state all the superficies of a PolyphyUia 

 are covered with numerous polypes, the bodies 

 of which are confluent at their margins. Their 

 mouths are placed without any regular order, 

 but open here and there in the depressions 

 that separate the numerous laminae ; they are 

 of an oval or roundish form, and slightly 

 fringed around their margins, but without any 

 tentacula. These latter are distributed over 

 the whole upper surface of the compound 

 animal, and seem to be formed by prolongations 

 of the fleshy substance which covers the more 

 prominent lamellae, but present no appearance 

 of being arranged round a given centre. When 

 taken out of the water they disappear, shrink- 

 ing between the laminae. The polypes them- 

 selves in their structure resemble those of the 

 other Anthozoa, presenting the usual arrange- 

 ment of a stomach and ovigerous filaments. 



Very nearly related to the Fungiae are the 

 McandrincB (fig. 40), the poly paries of which 



Fig. 40. 



B 



A. Meandrina cerebriformis. 



B. A portion magnified, showing the polypes oc- 

 cupying the bottom of the furrows. (After Quoy et 

 Gaimard.) 



are globular, their surfaces being grooved with 

 sinuous furrows, the meanderings of which 

 give name to the genus. The Meandrinae 

 have all a determinate growth which they do 



