170 Prov 'cdiiiU'^ of the Roi/dl ^Society of Victoria. 



however, the dactylopores on the inner side of the system always 

 disappear, and at a still later date the systems may be seen to be 

 almost entirely obliterated. The gastropores are provided with 

 styles, which are short and stout, and in the dactylopores a style 

 is represented by a toothed plate on the outer wall. Within the 

 gastropore, about the level of the top of the style, is a ring of 

 projecting teetli, which thus divide the chamber into two portions 

 an inner and an outer. In some of the specimens, ampullae are 

 very numerous. In one example for instance there was a row of 

 five confluent ones on one face and four on the opposite face, 

 while in another instance there were several, perhaps Iialf a dozen, 

 so massed together that they could not be clearly separated. The 

 outer walls of the ampulhe are very thin and liable to be broken 

 down. In the unbroken ones there is to be seen, in some cases, 

 a fairly definite opening leading into the interior. The edges of 

 these openings are rounded off" so that they do not appear to 

 be due to fractures. They occupy the places, in some cases at 

 any rate, of the slit-like pores of the external surface and from 

 which they are probably developed. Reference was made to this 

 character in the pi*evious paper and it was inferred that the definite 

 nature of the opening implied a constant succession of escaping 

 planuhe. The inner basal wall of the ampulla generally shows a 

 large pore about its centre. 



In some well preserved specimens the cord-like ridges of the 

 surface were seen to be crossed by fine ridges or strife. 



Anastomosis of two branches was noted in one instance, while 

 in some others the corallum had almost entirely wrapped round a 

 stem of Isis, which it crossed diagonally. 



A series of measurements of Dcoiitopora was made and compared 

 with a corresponding series of Stylaster sp., which show that 

 the cyclosystems and pores of the fossil are considerably larger 

 than those of the recent form. 



The diameters are as follows, the figures being millimeters. 



Cyclosjstem. Gastropore. Dact\ lopore. 



Deontopora - - 1-0 to 0-8 ... 0-5 to 0-2 ... 0-U to 0-07 

 Stylaster - - 0-6 to 0-5 ... 0-3 to 0-2 ... 0-07 to 0-0.> 



In the original de.scription the affinities of the genus were left 

 undecided. It will be seen that the relationship to Stylaster is 



