H. O. Carruthers — A Revision of some Carboniferous Corals. 27 



Remarhs. 



Under tiie name of Hadrophyllmji Edwardsianum, de Koninck 

 described (Nouv. Recher., p. 52, pi. iv, figs. 2, 2a), in my opinion, 

 a young specimen of Z. omaliiisi. He carefully described tbe 

 strongly quadrate arrangement of tbe septa in the calyx, and the 

 development of a counter fossula (on account of the latter character 

 he referred the specimen to the genus Hadrophyllum), features which 

 are seen to be characteristic of the young stages of growth of 

 Z. omaliusi, though obscured in adult calices, and I have no 

 hesitation in referring the specimen to that species. An examination 

 of his figured specimen showed that it was much weathered ; to this 

 fact the unusual depth of the epithecal ribbing is due, as also the 

 presence of a small median groove down the centre of eacb of the ribs, 

 a fact to which de Koninck drew attention in his description. This 

 latter character is not, however, of any specific value, but may be 

 found in any much weathered Zaphrentid corals. 



Z. omaliusi can, as a rule, be readily separated from other 

 Zaphrentids. Z. pliillipsi, M.-Ed. & H., has a certain resemblance, 

 but according to the authors' account possesses very thin major septa, 

 with a curvature (according to the figure in the " British Fossil 

 Corals," pi. xxxiv, fig. 2h) convex, instead of concave, to the large 

 fossula, which also has a long dividing septum in the calyx. Eadical 

 differences are also shown in the epitheca, which in Z. phillipsi does 

 not seem to have longitudinal ribbing, and above all is frequently so 

 affected by rejuvenescence as to have its continuity interrupted (see 

 Polyp. Foss. d, Terr. Pal,, pi. v, fig. 1). The differences from 

 Z. delanouei will be referred to presently wben dealing with that 

 species. 



Some resemblance to Z. omaliusi is occasionally displayed in 

 the calyx of a young specimen of Caninia cornucopice, Mich, {non 

 M.-Ed. & H.). But besides other differences the fossula in this latter 

 species is deeper and longer, and in transverse sections is seen to be of 

 a totally different character, being open at its inner end with the 

 flanking septa usually disconnected, while in transverse sections the 

 septa in the two cardinal quadrants are always affected by accessory 

 thickening, a feature never seen in L. omaliusi. 



With the exception of the two varieties to be immediately described 

 the nearest corals to Z. omaliusi seem to be Densiphyllids, especially 

 D. charlesto7iensis, Thom. These are, however, fundamentally 

 distinguished by the possession of a most inconspicuous cardinal 

 fossula, narrowing continuously to the centre of the corallum, and the 

 major septa are almost purely radial in disposition, altogether lacking 

 the characteristic curvature of those in Z. omaliusi. 



Distriiution. 

 The species seems quite local in its occurrence. Dr. Vaughan has 

 kindly supplied an account of its distribution in the South- Western 

 Province, but as it will be more convenient to insert these notes after 

 the description of Z. delanouei, it is sufficient to mention that in that 

 region Z. omaliusi attains its maximum in the Upper Tournaisian 

 subzone Z,, while it is again common in the Upper Tournaisian Rush 



