Vol. 62.] LIMESTONE OE THE MENDIP AREA. 331 



rather than as the base of the Syringothyris-Zone, for the following 

 reasons : 



(1) The brachiopod-fauna is, as a whole, essentially similar to that of the 



Upper Zaphrentis-Zone. Special points of resemblance are : the 

 abimdance of Spirifer aff. clathratus and var. and Chonetes cf. har- 

 drensis, and the common occurrence of Leptana analog a and Productus 

 aff. pustuloszts. 



(2) Zaphrentis aff. Phillipsi and Z. aff. cornucopia, which are both abundant 



at this horizon, are essentially Zaphrentis-Zone forms, being very rare 

 in the Syringothyris-Zone. (The mutation of Zaphrentis aff. cornu- 

 copia, which occurs commonly in the latter zone, is easily distinguished 

 from the typical Z 2 form.) 



The specialfaunal characters, which Horizon y possesses in common 

 with the Syringothyris-Zone, are the following : 



(1) The common occurrence of Syringothyris aff. cuspidata, mut. C. 



(2) The abundance of Orthothetes aff. crenistria, mut. C. 



(3) The abundance of Schizophoria aff. resupinata. (This form attains its 



maximum immediately above Horizon y.) 



(4) The occurrence of Caninia cylindrica. (Caninia cylindrica persist* 



throughout the Syringothyris-Zone.) 



(5) The occurrence of Syringopora cf. reticulata. 



C = Zone of Syringothyris aff. cuspidata, mut. C. 

 (SmmGOTSYHis-Zone r ) 



General lithological character. — Massive limestones. The 

 lowest beds are slightly dolomitic, but the main part of the zone 

 consists of fairly-pure l limestones, which are more or less oolitic, the 

 local development of oolites being sometimes considerable. 



Coral-fauna (omitting Horizon y): 



Zaphrentis aff. Phillipsi. 

 Zaphrentis aff. cornucopia, mut. C. 

 Caninina cylindrica, muts. 

 Caninoid Cyathophylla. 

 Cyathophyllum <p. 

 Campophyllam caninoides. 



Amplexus sp. 

 Michel inia megastoma. 

 Syri?igopora cf. reticulata. 

 Syringopora cf. distans. 

 Lithostrotion cf. irregulare. 

 Early Clisiophyllids. 



Brachiopod-fauna (omitting Horizon y) : 



Orthothetes aff. crenistria, mut. 0. 

 Bhipidomella aff. Miehelini. 

 Schizophoria aff. resupinata. 



Seminula ambigua. 



Seminula aff. ficoides. 



Athyris cf. expansa. 



Athyris cf. glabristria. 



Beticularia, cf. reticulata. 



Spirifer aff. clathratus. 



Spirifer cf. bisulcatus. 



Spirifer cf. striatus. 



Syringothyris aff. cuspidata, mut. C. 



Syringothyris aff. laminosa. 



Pugnax cf. acuminatus. 



Derby a sp. 



Productus cone inn o-Martini. 



Productus aff. Cora, mut. C. 



Productus 6. 



Productus pustuloso-fimbriatus. 



Chonetes cf. hardrensis. 



Chonetes cf. papUionacea. 



Chonetes cf. comoides. 



Subdivisions. — None; excluding Horizon y, which is best 

 regarded as the top of the Zaphrentis-Zone (see above, p. 330). 



1 The limestones of this zone are extensively burnt for lime. 



