176 TABULATE CORALS. 



Lastly, these sections occasionally show mural pores, though 

 these structures can be best made out by a microscopic exami- 

 nation of the exterior of the tubes, when they are found to be 

 present in the form of small, circular, irregularly-distributed 

 apertures. It may be added that long sections show the same 

 curiously puzzling feature as do tangential slices namely, that 

 the corallites are apparently in contact throughout their length, 

 whereas macroscopic examination shows them to be clearly free 

 over the unthickened segments of the tube. 1 



So far as can be at present ascertained, the species properly 

 belonging to Stenopora, Lonsd., as now worked out, are all 

 confined to the Carboniferous or Permo-Carboniferous periods, 

 there being some uncertainty as to the precise horizon of some 

 of the deposits which have yielded specimens of this type. So 

 far as known, also, the species of the genus are confined to 

 Australia and Van Diemen's Land. It cannot be said that any 

 species of the genus has been certainly identified in the Silurian 

 rocks, and all the Silurian corals which have been at various 

 times referred here must in the meanwhile be placed under 

 Monticulipora or Chcetetes pending their complete examination 

 by microscopic methods. The internal structure of Stenopora, as 

 I have here described it, is such as to fundamentally separate 

 the genus from either Ch&tetes or Monticulipora', but I am 

 unable to say how far a mere examination of the surface with 

 a lens would enable an observer to separate a specimen of the 

 first from one belonging properly to either of the latter genera. 

 None of my examples, in fact, show the surface-characters in 

 a satisfactory manner ; but so far as I can judge, the general 



1 Since the foregoing has been written, examples of Stenopora Tasmaniensis, 

 Lonsd., S. crinita, Lonsd., and of a third form apparently referable to S. informis, 

 Lonsd., have been carefully examined by Mr R. Etheridge, jun., and myself. The 

 phenomena which these present v/ill be elsewhere recorded by us, and it will be 

 sufficient here to say that all the above species are true Stenoportz, though the two 

 last are massive, and in many respects widely unlike S. ovata in general appear- 

 ance. All of them, however, possess the peculiar fibrous thickenings of the walls of 

 the tubes in parts, and must therefore be regarded as congeneric with S. ovata. 

 They show, nevertheless, many very singular features, the two last in particular not 

 only differing considerably from S. ovata, but also differing in important characters 

 from one another. 



