OF DENISON UNIVERSITY. 



13 



on account of the unequal compression of the polyps. Their walls 

 are not perforated, those of adjacent polyps are not intimately con- 

 nected so that in case of fracture, the coral often splits along the 

 middle of these walls Weathering will often loosen the polyps in a 

 similar way. The broken coral then assumes a columnar appearance. 

 The columns are longitudinally corrugated at regular intervals by 

 continuous ridges, five or six on each side of its polygonal outline; 

 and also transversely corrugated, but at very irregular intervals. 

 There are also numerous transverse striae, which appear under a lens. 

 Interiorly it consists of about thirty-five lamellae which extend from 

 the walls towards the centre. The gre iter part disappear before 

 reaching a distance within one milllimetre of the centre, and of the 

 -rest occasionally one or two reach the very centre; in that case some- 

 of them sometimes seems to pass on for a slight distance beyond the 

 center. The spaces between these lamellae are occupied by vesiculose 

 leaflets or dissepiments. 



We do not believe that this species is really identical with the 

 French species, but the structural similarity is greater with this si)ecies 

 than with any other known to us. The Australian form however has 

 a smaller number of lamellae, in a cross section they are seen to be 

 often more or less wavy, and not uniformly straight as our figure 

 would indicate, the number of disseppiments is also slightly less 

 numerous than there represented. The general effect is however well 

 given. These minute differences were noticed after the drawings 

 were made. It differs from C. hexagonum, Goldfuss in the absence of 

 a zone of thickening in the lamellce about the centre of the polyp. 

 From C. rugosum, Edw. and Haine it differs according to Rominger's 

 identifications, in the much smaller number of dissepiments, and in 

 the fact that the lamellae do not lose their character at a certain dis- 

 tance from the centre and then continue are mere ridges over the 

 tabulae. The interior termination of the lamelUi: is Hir more regular. 



While our specimens show a close structural affinity with C. 

 Boloniense, the fact that we have not well preserved views of the 

 calyces prevents our determining whether the slight variations 

 observed are specific or varietal in nature. 



ENDOPHVI.LUM . 



{Plate XIII, Figs. 16, 17.) 

 Corallum composed of numerous polyps, jiolvgonal or hexagonal 



