180 Dr. H. A. Nicliolsou and Mr. il. Etheridge, Juu., 07i 



are nearly vertical, with comparativelj thin walls, and poly- 

 gonal in shape. In the peripheral region of the corallum 

 the corallites bend outwards nearly at right angles to the axis, 

 the walls becoming thickened and being entirely fused with 

 one another, while the visceral chambers become oval or 

 rounded. The periodical thickenings of the walls of the 

 tubes in the final portions of their course are mostly long and 

 fusiform, and are generally placed at corresponding levels in 

 contiguous corallites. The average diameter of the corallites 

 is about ^ millira. In the walls of the corallites in the peri- 

 pheral region acanthopores are developed in great numbers, 

 their shape being usually oval or subangular, their size large, 

 and their walls not specially or only slightly thickened. 

 Tabular are very sparingly developed, and are only occasion- 

 ally to be recognized at all. 



Obs. In its general form this sj^ecies closely resembles S. 

 ovattty Lonsd., and the typical examples of 8. tasmaniensis, 

 Lonsd. From these two species, however, the present form is 

 distinguished, among other characters, by the extraordinary 

 abundance and large size of the acanthopores. S. Hoicsii, 

 Nich., has also very numerous acanthopores, but these are for 

 the most part very minute, and the annular thickenings of the 

 wall are quite ditFerent, while the tabulai are very numerous 

 and are perforated. The acanthopores are best seen in tangen- 

 tial sections (PI. III. fig. 7) ; but they are also well exhibited 

 in sections of the peripheral region of the corallum, cutting 

 the corallites longitudinally, in which they appear as delicate 

 clear tubes running in the thickened walls of the corallites 

 (PL III. fig. 8). Tabulse are often not to be detected^ and 

 when present are very few in number. In tangential sections 

 appearances are occasionally to be detected which may per- 

 haps be caused by the existence of perforated tabulae ; but as 

 the specimens are in a very peculiar condition of preservation 

 this cannot be affirmed with certainty. None of our speci- 

 mens exhibit the surface of the corallum, and we therefore do 

 not know if the mouths of the corallites were closed at tlie 

 final period of growth by the development of a perforated 

 tabula, as seems to have been sometimes the case in S. tasma- 

 niensi's, Lonsd., and probably in S. austrah's, nobis. 



Formation and Locality. The specimens of this form which 

 we have examined are from a purplish ferrugino-micaceous 

 rock, of Permo-Carboniferous age, from Pelican Creek, half 

 a mile above Sonoma and Bowen-Road Crossing, Bowen- 

 River Coal-field, North Queensland. [Coll. Geol. Survey, 

 Queensland.) 



