270 Dr. H. A. Nicholson and Mr. R. Ethericlge, Jun., on 



Galles du Sud,' Prof. L. G. de Koninck has shown the exis- 

 tence in Stenopora ovata of mural pores or perforations *, and, 

 in consequence, has referred it to the genus Favosites. The 

 pores in question are described as irregular in disposition, 

 some on the faces of the walls themselves, others on the 

 angles of the corallites. The presence of tabulas, first figured 

 by Lonsdale in Stenopora, is recorded in this species. 



Oos. Taking >S*. ovata, Lonsd., as the foundation of the 

 following remarks, the corallum in Stenopora is usually more 

 or less branched ; but the branches may be so thick, or may so 

 extensively coalesce, that its general form becomes that of a 

 lobate mass. The corallites (fig. 1, A) radiate in all direc- 



Fi S '. 1. 



\m\mmmW\ 



A. Portion of a branch of Stenopora Jackii, Nich. & Eth., Jun., split 

 open, of the natural size. B. Portion of the same, enlarged, 

 showing- the annulation of the tubes in their outer portions. C. A 

 few of the tubes of the same, still further enlarged, showing the 

 mural pores. Permo-Carboniferous, Queensland. 



tions from an imaginary axis, and present very different 

 appearances in the central and circumferential portions of the 

 corallum respectively. In the axial portion of the branches 

 the tubes are nearly vertical, are essentially polygonal or 

 prismatic in shape, have thin walls, and are nearly or quite 

 in contact with one another throughout. As they pass up- 

 wards the tubes gradually diverge, coming, at last, to be 

 nearly horizontal, and preserving this direction for a consider- 

 able distance, till they at last open upon the surface. There 

 is thus an exterior zone of the corallum, in which the coral- 

 lites are nearly transverse to the axis of the branches ; and in 

 this region (fig. 1, B) they have a generally cylindrical ap- 

 pearance, owing to the fact that their walls are thickened at 

 very short intervals by annular accretions of growth, the por- 

 tions of the tube between them retaining their normal dia- 

 meter. As these thickened portions are placed at corre- 



* Bruxelles, 1877, pt. 3, pp. 156, 157. 



