92 MADEEPORARIA. 



growth, his species pulvinaria belongs to another and less specialised, viz. to the explanate 

 method of growth. 



There are in all ten specimens, some of the smaller of which are apparently fragments of a 

 large growth. They are all from Tongatabu. The largest is a smooth, cushion-shaped mass 

 resting upon the edge of an overturned dead mass of the same coral. Sections of some of 

 the broken specimens reveal very beautifully the manner of growth. The calicles rise nearly 

 straight up from their bases, those at the sides, however, soon bending outwards. This 

 continued bending outwards of a certain number of calicles makes room for new ones to 

 appear in the middle. In this way, the top continually expands. The sides of the growth 

 on which the calicles first bent outwards opened, die progressively upwards and are grown 

 over by a film not unlike an epithecal covering and perhaps physiologically identical, though 

 hardly morphologically. The uppermost layer remains alive and greatly expands, bulging 

 out on all sides over its dead pedestal. This layer is again continually covered with fresh 

 layers, ultimately becoming top-heavy and rolling over. 



The specimens fortunately contain a complete series showing all the stages of growth 

 here sketched. 



Three specimens show the starting into fresh life of broken, overturned fragments. In 

 one case [Register No. 91. 3. G. 95.], the fragment has started growing on opposite sides, 

 and affords another interesting illustration of the striking variations in one and the same 

 specimen, to be attributed evidently to different conditions of growth. If the two growing 

 patches were not parts of the same specimen, they would never be thought to belong to one 

 and the same species. 



a. Tongatabu. J. J. Lister, Esq. (Type.) 



l-j. Tongatabu. J. J. Lister, Esq. 



Species 7. Astrsopora ehrenbergii. (PI. XXXIII. lig. 15.) 



Astrceopora myriophthalma, Klunzinger (non Lamarck), Korallenthiere des rothen Meeres, ii. (1879) 



p. 52. 

 Phyllopm-a sphwrostoma et leptostoma, Ehrenberg, Korallenthiere des rothen Meeres, 1831, p. 114; 



vide Klunzinger, I.e. 



Description. — Corallum shows the pulvinate type of growth. 



Calicles slightly protuberant along the top of the ridge; the protuberances irregularly 

 hemispherical, here and there coalescing, owing to their irregular distribution. On the 

 overhanging portions of the expanded top, the calicles tend to be smaller and more star-like, 

 1 to 1 • 5 mm., as compared with 2 to 2-5 mm. along the top. The margin of the calicle is a 

 rough, jagged reticulum, or a ring of erect spines ending in fine points and connected by 

 trabeculse. The twelve septa appear at the margin and descend as well-marked ridges in two 

 distinct cycles ; deep down, the primaries throw out interlacing processes, which, when well 

 developed, may together fill up the central region of the fossa. 



The ccenenchyma is evenly echinulate, the echinulae crowded, short, and thick round the 

 slopes of the calicles, finer in the interstices. All alike end in irr^ular groups of fine 

 diverging points. The floors in the wider interstices with large pores, but evenly developed 

 in regular tiers. In section, the two typical elements, costal and synapticular, are beautifully 



