48 



Descriptions of New Species of Corals 

 FROM THE Australian Tertiaries. 



By J. Dennant, F.G.S. 



[Read May 7, 1901. ] 

 Part III. 



Plate II. 



In the present paper I remark further upon the genus 

 Tre^natotrochus, and describe three additional species belonging 

 to it. 



In Part I. of this series of articles I placed the genus Tremafo- 

 trochus amongst the Eupsammidie, in the section Madreporaria 

 Perforata, because both in Tenison Woods' type species, T. 

 fenestratus, and in T. Clarkii, the new one described, there are 

 intercostal pores in the wall. A similar perforation of the wall 

 is also conspicuous in T. complanatus and T. laterophnus, species 

 described in Part II. Since doubt has been expressed by some 

 European writers as to the actual penetration of the mural pores 

 in Woods' species, I take the present opportunity of supplying a 

 drawing of the internal wall, as seen under the microscope by 

 transmitted light. A specimen was hardened with Canada 

 balsam, mounted on a slide, and then divided longitudinally, the 

 inner as well as the outer surface of the mounted half being left 

 intact. That light is now freely admitted through the pores is 

 evident from the drawing (PI. II., fig. 1). I have next to call 

 attention to two interesting corals, in which the wall, though 

 fenestrated in the manner characteristic of Trematotrochus, is not 

 actually perforate. The intercostal spaces are, as usual, regularly 

 crossed by thin transverse bars, with pore-like cavities between ; 

 but the latter do not penetrate the theca. In external appear- 

 ance, as well as in the arrangement of their septa, costae, (fee, 

 these species are analogous to the Trematotrochi already described, 

 and I, therefore, include them in the same genus. My revised 

 diagnosis of that genus will, I consider, admit them, the wall 

 being described as incomplete in the intercostal spaces, and 

 regularly fenestrated. By their inclusion, however, it becomes 

 necessary to review the position of the genus itself in the 

 madreporarian series. 



Of the seven species now known, T. Clarkii, the only Miocene 

 one in the genus, has strong Eupsammian affinities. Two of 

 those figured below, viz., T. Kitsoni and T. decUvis, might 



