﻿146 MADEEPOKAEIA. 



I. A singularly beautiful specimen from Diego Garcia (PI. XXV.) consists of a tangled 

 mass of thick branches (2 cm.) with very stout trabecula?, and showing all the typical trabecular 

 formations. Explanate portions developed here -and there. Colour, a light fawn tinged with 

 rose-red (cf. specimen g). 



c. A corroded specimen from Aden is especially interesting, because it shows a fiat ex- 

 planate growth 17 cm. long and 8 to 9 broad. From the centre of this, columns arise from 

 thin bases and swell out into great nodulated masses 7 to 8 cm. high, which fuse together ; 

 worm-tubes opening irregularly over the surface. This is a departure from the type, but the 

 essential characters agree with those described for a and h. 



d. In another specimen from Aden the tips of many of the fused branches show a great 

 proliferation of tlie axial reticulum. This, in many cases at least, succeeds in burying the worm- 

 tube. Worm-tubes in all stages of disappearance, beneath the white, wooUy-looldng papillse 

 which cap so many of the fused branches, can be found. The last stage of closing might 

 be mistaken for a calicle, viz. a deep funnel-shaped hole set all round with ecliinulne not 

 unlilce septa. The explanate encrusting portions are fragmentary and irregular, one is 

 encrusting and apparently destroying a large Mussa. The specimen owes perhaps some of its 

 irregularity to the swarms of Balanids which have settled upon it. The calicles are much 

 larger than in c, and the tubercles more light and reticulate. Some of these differences may 

 be due to the corrosion which c appears to have undergone before collection. 



c,f. Two almost pui-ely horizontal explanate growths, about 2 mm. thick at the growing 

 edge, and 6 to 8 mm. in older parts, with well developed epitheca extending to within 2 to 3 cm. 

 of the growing edge, which is slightly turned up as in Dana's type. These specimens differ 

 greatly in external appearance, both from one another and from the foregoing. Yet they are 

 united together by being both tuberculate, in having very similar textures in section, and the 

 same method of growth. And, finally, they are united with the foregoing specimens by the 

 fact that here and there worm-tubes commence to form short branches (although not yet 

 reaching more than 1 cm. high), and on these the tubercles show the usual tendency to form 

 plates. 



g. Tliere is, further, a specimen which differs in appearance again from any of the 

 above. It is explanate, much distorted by Balanids and sediment, and is suffused with a rose- 

 pink colour, and the growing edge is closely followed by the epitheca. The alKance with the 

 above, however, is shown by its ccenenchyma.tous specialisation being the same. The 

 tubercles form plates arranged at angles with one another, and there is a tendency to form 

 branches encrusting small worm-tubes, the crenenchymatous plates being especially rich on 

 elevations, at least as soon as they reach a certain thickness. In this specimen the few 

 incipient branches round worm-tubes are still too thin to show the plate formation, but 

 this is seen on certain upgrowths from the surface and round a di-ooping lower edge. This 

 specimen may well be the explanate form of such a specimen as that above described from 

 Diego Garcia (b). 



h, i, J. Lastly, there are three broken fragments which have all the appearance of being 

 portions of the explanate bases of a specimen like those described above. One (A) was 

 labelled ilontipora scahrimla, Dana, but, in its coenenchymatous specialisations it agrees 

 essentially with the type, and from its close resemblance to c must, I should think, have come 

 from Aden. 



All these very different looking specimens are united by the following characters : (1) 

 initial or at least partial explanate gi'owth ; (2) tuberculate with radial ridges round the 



