PHOTOTYPE PLATE NO. IT. g 



measures, as shown in the diagram, no less than nineteen feet. It is split up, on its seaward side, 

 by two convergent intersecting gutters, and is separated on its northern, shorewards, face from the 

 adjacent coral-mass by a channel over a fathom deep, which measured exactly two feet wide, 

 at its narrowest point, when the two masses were awash at dead low spring tide. 



Notwithstanding its present massive proportions and irregularity of contour, this huge 

 Porites began as a small, symmetrically convex, corallum a few inches only in diameter, or, 

 to be more accurate, from a single polyp of microscopic dimensions — from such a one, in 

 fact, as is delineated among the representations of this genus included in Plate VIII. of the 

 coloured series. The mind conjures up, intuitively, the number of the centuries that must 

 most assuredly have elapsed since the primaeval nativity of this gigantic coral. 



In its present condition of growth, this Porites is living, and increasing in size, on its 

 peripheral edge only, all vitality being arrested on its superior surface in consequence of its 

 having attained to a vertical height that exposes it, periodically, to atmospheric influences inimical 

 to healthy growth. This more elevated plane, although unfavourable to the further vertical 

 enlargement of the Porites, is not unsuited to the growth of many other species, which are 

 accordingly found flourishing on its dead horizontal surface. None of these superimposed corals 

 were in June, 1890, of conspicuous size. The largest, a Coeloria, measured three feet four inches 

 across its longest diameter, while the majority of the specimens, representing the several genera 

 Pocillopora, Goniastrasa, Mussa, and Madrepora, in no instance, as shown in the accompanying 

 diagram, exceeded a width of twelve inches. A systematic record of the further growth of these 

 comparatively young corals is specially recommended, and should elicit data of high interest and 

 importance. 



The second, more inshore, coral-mass indicated on the diagrammatic chart, is of smaller 

 dimensions than the outer one, and measured but eight feet two inches in its longest 

 diameter at the date recorded. It is also of a species distinct from that of the larger 

 outside mass, being a Goniastrasa, allied to G. cxiniia, in this instance greenish-white in hue, 

 and having much larger constituent polj'p-cells or corallites than the Porites. The channel 

 separating these two contiguous masses was, as previously stated, at the date recorded, pre- 

 cisely two feet wide. It would be instructive to ascertain the time that will elapse before 

 this channel becomes filled up bj' the growing corals, or otherwise what progress towards 

 the accomplishment of such a result will be made within the next few decades. As 

 indicated in the diagram, a symmetrical colony-stock of one of the procumbent species 

 of Madrepora, M. prostrata, three feet eight inches in diameter, is interposed between the 

 two main coral-masses, occupying a position to the extreme left of the intersecting channel. 

 A smaller, more deeply submerged, growth of the same species projects yet further into this 

 channel at the point indicated by the dotted line. This highly porous, loosely-branched species 

 of Madrepora, it may be confidently assumed, spreads peripherally at a much more rapid 



