CORALS AND CORAL-ANIMALS. 165 



species of Brain-stone corals just enumerated, will be found in Plate V. of the chromo-litho- 

 graphic series. 



A point of interest is attached to the small rectangular area numbered i8a, in the left-hand 

 bottom corner of the plate just named. It represents a basal area of the corallum of the Coeloria 

 delineated in Fig. 18, in which two new polyp centres are making their appearance in the 

 connecting substance or "cosnosarc." In the centre, farthest to the left, the polyp is single 

 and circular, like that associated with the single corallite of the species of Favia, indicated 

 by Fig. 14, a little higher up. In the polyp centre to the right, fission of the primary 

 polyp has already proceeded to such an extent, that two independent oral apertures occupy 

 the clearly defined peristomial area. It is by repeated incomplete fission of a corresponding 

 nature that the elongated, more or less devious, polyp-valleys of this and the many allied 

 "Brain-stone" corals are gradually built up. 



There is one other specimen included in Chromo plate V. that invites brief notice. This is 

 represented by Fig. 9, a single large green, polygonal, central corallite and two small lateral cups 

 which have been produced from the larger corallite by the process of lateral gemmation. The 

 species is identical with the Mosclya latistcllata of Quelch, one of the most interesting of the 

 Madreporaria collected by the Challenger expedition. The importance attached to this coral is 

 associated with the fact that it is, structurally, more nearly allied than any known living type to 

 the ancient paleozoic genus Cyathophyllum, and finds its natural position within the same family 

 group of the Cyathophyllidae. The most essential diagnostic features of the Cyathophyllidae, 

 which includes a larger paleozoic sectional group of the Rugosa, are that the septal elements 

 are represented by multiples of four, instead of by six, as obtains in all other known existing 

 Madreporaria, as also the constant presence of horizontal partitions known as " tabulae," which 

 give to the corallite, in section, a distinctly camerated plan of structure. The single specimen 

 obtained by the Challenger was dredged off Wednesday Island, in Torres Strait, at a depth of 

 eight fathoms. Examples of the same species were collected by the author, at both Thursday 

 Island and in the Albany Pass, Torres Strait, growing on the reefs at extreme low water 

 mark. As indicated in the accompanying illustration, Chromo V., Fig. 9, the colour of the 

 living corallite is, with the exception of the oral area, an intense emerald-green. A species 

 closely allied to this form has been collected by the author, in the neighbourhood of 

 Port Darwin. The occurrence of this paleozoically-allied coral on the Australian coast, in 

 conjunction with this region, representing the only one that now produces living Trigoniae, 

 forms an interesting pendant to the geologically ancient affinities of the Australian terrestrial 

 and aquatic fauna, as exemplified by the Marsupial and Monotreme mammals and Osteoglossum 

 and Ceratodus among the fresh-water fish. 



The sub-section of the Star-corals, represented by what are technically known as the typical 

 Astraeaceae, remains to be mentioned. The members of this group differ from Goniastrcca and 



