POLYPIFERA. 



37 



not exceed, and consequently their masses 

 are always separate, and not agglomerated like 

 those of Madrepores, Astreae, &c., which grow 

 indefinitely. The polypes of Meandrinae oc- 

 cupy the bottom of the furrows, and are va- 

 riously coloured in different individuals. When 

 attentively examined, they are seen to form 

 membranous expansions, which 

 cover the lamellae of the ambu- 

 lacra but rarely mount to the 

 summit of the ridges, the white- 

 ness of which indicates the line of 

 separation between the different 

 rows of polypes. They are, in 

 fact, Caryophylliae or Fungiae 

 much elongated. They secrete, 

 from all parts of their body, a 

 mucosity so abundant that, on 

 reversing the mass, it runs off" 

 like albumen. The same is the 

 case with Agaricae and Pavoniae. 

 When exposed to the sun the 

 living part becomes black by pu- 

 trefaction. 



species already described ; the principal differ- 

 ence between them being in the number of 

 the tentacula, corresponding to that of the 

 radiating lamellae, wherewith their bases cor- 

 respond, which, in the many-armed species, 



Fig. 42. 



CaryophyUia 

 has 



On splitting the globular stony polypary of 

 a Meandrina, the mode of its growth is very 

 beautifully demonstrated. Commencing at the 

 centre of the mass, the deposition of calcareous 

 matter is seen to have progressed regularly in 

 all directions, layer after layer, like the coats 

 of an onion, every stratum having, of course, 

 in turn been the outer surface of the polypary 

 and marked with the same sinuosities or con- 

 volutions as are exhibited by the existing ex- 

 terior, affording a very striking illustration of 

 the mode of growth common to all the litho- 

 phytous zoophytes, and of the mathematical 

 precision with which they build their wonder- 

 ful edifices. 



We are progressively conducted through 

 various intermediate species of laminated zoo- 

 phytes from the broadly extended disc of 

 Fungia and the diffuse surface of Meandrina 

 to more concentrated forms of these lithogenic 

 polypes. In Turbinolia (fig. 4-1), for example, 

 the superior laminiferous disc is evidently an 

 approximation to the structure of the real 

 polype-bearing cells of CaryophyUia (fig. 

 42), where the stony polypary is made up 



Fie. 41. 



fasciculata. A portion of the calcareous polypary 

 been denuded. (After Quoy et Gaimard.) 



are numerous. Another important circum- 

 stance in the economy of these races of zoo- 

 phytes is, that the radiating lamellae contained 

 in the abdominal cavity situated beneath the 

 stomach are progressively calcified from be- 

 low upwards, and thus become converted into 

 stony plates instead of membranous septa, 

 so that on making a section of these poly- 

 paries perpendicular to the axes of the cells, 

 each cell presents the appearance repre- 

 sented in^g. 43 ; and even in fossil polyparies, 



Fig. 43. 



Turbinolia rubra. (After Quoy et Gaimard.)] 



of infinite numbers of distinct cells united 

 to each other by an interposed calcareous ce- 

 ment, and every one of them containing a 

 many-armed polype, the essential structure of 

 vhich is similar to that of the eight-armed 



Section of calcareous polypary of Astrea abnormalis. 

 (After Quoyet Gaimard.) 



where the whole substance of the mass has 

 become solidified, the original radiating lamina? 

 are permanently conspicuous, as many a mar- 

 ble chimney-piece will testify. In their living 

 state the polypes inhabiting these cells are 

 most variously and gorgeously coloured, so 

 that when protruded they are indescribably 

 beautiful, resembling the flowers that adorn 

 the gayest parterres in our gardens. Yet if 

 such be the interest of this spectacle, even to 

 the eye of the ordinary observer who amuses 

 himself by contemplating the indications of life 

 exhibited by a little patch of a coral reef, what 



D 3 



