52 



The cost^e, which are continuations of the septa, are stout and 

 prominent on the wall. The primaries and secondaries are equal, 

 and a little thicker than the tertiaries and quaternaries, which 

 are also equal. All gradually diminish in size towards the base 

 of the corallum. The first three cycles unite at the base, and the 

 tertiaries are joined by the quaternaries a little higher up. Each 

 intercostal space is crossed by a regular series of transverse bars, 

 with pore-like cavities between. In one specimen T counted 27 

 bars, with their corresponding cavities, between two adjacent 

 costte. As in the case of T. Kilsoni, these cavities do not penetrate 

 the wall, which is continuous within the calycle. Similarly, also, 

 the theca of this coral is stout, except where reduced in thickness 

 by the series of cavities in the intercostal spaces. 



Height of corallum, 7*5 mm.; length of calice, 8-6 mm.; 

 breadth of calice, 7-8 mm. These are the dimensions of the 

 type. A larger specimen obtained lately is 10 mm. high, and has 

 an almost circular calice, its diameters being respectively 10 mm. 

 and 9-5 mm. 



Localities. — Rare in an outcrop of the older Eocene at the 

 mouth of Brown's Creek (adjoining Joanna River), on the south 

 coast of Victoria. Four specimens, of which one is less than half 

 the size of the type. 



This species, as well as the section in which it occurs, was dis- 

 covered by Mr. Kitson in 1899. 



Trematotroehus Mulderi, spec. nor. PI. ii., figs. 4a, b. 



Corallum small, free, very much compressed, and long in pro- 

 portion to its breadth. Both the anterior and lateral surfaces 

 slope gently to a flatly rounded base. 



Calice subplane and elliptical, with its diameters in the ratio 

 of 100 to 59. 



Septa straight, free, and in six systems, with three complete 

 cycles, of which the third is very thin, and projects but a short 

 distance into the calice. The two principal orders are stout, 

 especially the primaries, and unite with the columella by lobed 

 and thickened ends. 



The columella is large, prominent, and elongate, with a nodular 

 surface. A transverse section of a corallum cut at about one- 

 third from the base shows a solid interior without a trace of the 

 septa or columella. In another example cut midway between the 

 base and calice the interseptal loculi are still open. A third 

 corallum cut longitudinally has the calycle solid almost to its 

 summit, but the former outlines of the septa are faintly marked 

 nearly to the base. Possibly the infilling of the visceral chambers 

 in this species is due to a secondary deposition of carbonate of 

 lime. As a fact, not only the corals, but other organisms from 



