328 



MR. T. E. SIBLY ON THE CARBONIFEROUS [May I906, 



Camarotoecliia mitcheldeanensis, though still abundant, is greatly 

 diminished in numbers. 



Productus bassus occurs rarely. 



Chonetes ' Buchiana ' is replaced, as an abundant form, by Ch. cf. 

 crassistria. 



Cleistopora afr\ geometrica occurs in this subzone, but is nowhere 

 common. 



Between the well-marked bassus- and octoplicata-sxibzoTies, occurs 

 a thick series of shales, which may be assigned equally well to 

 either subzone, since it does not possess the characteristic features 

 of either one. This part of the zone is marked by the great 

 abundance of a Chonetes, intermediate between Ch. ' Buchiana ' and 

 Ch. cf. crassistria. 



Z = Zone of Zaphrentis aff. Phillipsi. 

 [Zaphejentis-TaOwq . ) 



General lithological character. — Massive limestones, in- 

 cluding much highly-crinoidal ' black rock.' In the lowest part of 

 the zone thin shales are interbedded with the limestones. Much 

 nodular and lenticular chert occurs, being most strongly developed 

 in the middle and upper portions of the zone. 



Coral-fauna : 



Zaphrentis aff. Phillipsi. 

 Zaphrentis aff. cornucopia. 

 Caninia cylindrica. 

 Cyathophyllum 9. 

 Amplexus cf. coralloides. 



Michelinia cf. favosa. 

 Michelinia cf. tenuisepta. 

 Syringopora 9. 

 Syringopora cf. reticulata. 



Braehiopod-fauna: 



Athyris Royssii. 

 Athyris cf. glabristria, units. 

 Martinia cf. linguifera. 

 Reticularia cf . reticulata.. 

 Spirifer aff. clathratus & var. 

 Spirifer cf. ductus. 

 Spiriferina cf . octoplicata. 

 Syringothyris aff. cuspidata, mut. K. 

 Syringothyris aff. cuspidata, mut. C. 

 Syringothyris aff. laminosa. 

 Camarotoechia aff. mitcheldeanensis. 

 Pugnax cf. pugnus. 



Leptcena analoga. 

 Orthothetes aff. crenistria, muts. 

 Rhipidomella aff. Michelini. 

 Schizophoria aff. resupinata. 

 Productus cf. Martini. 

 Productus cf. semireticulatus. 

 Productus aff. pustulosus. 

 Productus cf. aculeatus. 

 Productus aff. Cora, mut. 

 Chonetes cf. hardrensis. 

 Chonetes cf. papilionacea. 



Subdivisions : — 



/3 = Horizon /3. 



This includes only the lowest beds of the zone. It is defined by 

 the association of Zaphrentis aff. Phillipsi and Spiriferina cf. octopli- 

 cata, and thus forms a horizon of overlap between the Zaphrentis- and 

 Cleistopora-Zones. Since its palseontological characters, excepting 



