Palaeozoic Corals from Northern Queensland. 275 



lites in the central portions of the corallum thin-walled, poly- 

 gonal, and closely contiguous ; but in the horizontal portion 

 of their course thickened by annular accretions, by which the 

 tubes are placed in contact, the intervening unthickened seg- 

 ments being free. Corallites on an average from T \j to -£$ inch 

 in diameter, tubes of smaller size being here and there interca- 

 lated among the larger ones. In the outer portion of the tubes 

 about six of the annular thickenings of the tubes and as many 

 unthickened segments occupy the space of one line. Tabula? 

 horizontal, complete, remote from one another as a general 

 rule, and, for the most part, placed at corresponding levels in 

 contiguous tubes, these levels having no evident relation to 

 the annular thickenings of the tubes. 



Obs. Having already given a full account, so far as our 

 materials permit, of the internal structure of the genus, we 

 need not go into details as to the minute internal structure of 

 the present species. Our specimens, moreover, do not exhibit 

 the surface in any manner that would enable us to give the 

 external characters of the species. That our specimens are 

 referable to Stenopora is proved beyond a shadow of doubt by 

 their microscopic structure ; and in identifying them with S. 

 ovata, Lonsd., we have relied chiefly upon the rapid diver- 

 gence of the tubes from the central bundle, and the great 

 number and close arrangement of the annular thickenings of 

 the corallites in the horizontal portion of their course, these 

 being sometimes so much developed as to give to the exterior 

 of the tubes a regularly crenulated appearance. The annular 

 thickenings are also unusually broad ; and many smaller tubes 

 are interpolated among the larger ones as the surface is ap- 

 proached. 



Our determination is the more to be relied on as we have 

 made a direct comparison between Mr. Jack's specimens and 

 Mr. Lonsdale's Strzeleckian type*, although, for reasons 

 previously explained, we have not had the advantage of ex- 

 amining the specimens upon which the species was originally 

 based by Mr. Lonsdale, and which were collected in Tas- 

 mania by Dr. Charles Darwin, F.R.S. 



Locality and Horizon. Permo-Carboniferous, Coral Creek, 

 Bo wen-River Coal-field, Queensland. 



Collector. R. L. Jack, Esq., F.R.G.S., F.G.S., &c. 



Stenopora Jackii, Nich. & Eth., Jun. (Woodcut, fig. 1.) 

 Spec. char. Corallum ramose, dividing at wide intervals, 

 the branches cylindrical, averaging about two lines in dia- 



* Phys. Descript. N. S. Wales, &c, 184.">, t. 8. f. (coll. Brit. Mas.). 



