148 



PROFS. LLOYD MORGAN AND REYNOLDS ON THE [May I9O4, 



Position of Beds re- 

 ferred to the section 

 north of the Avon at 

 Bristol. 



Sequence. 



Palaeontological characteristics. 



Lower part of Great"") f Marked by the entrance of Lithostrotion, 



Quarry and underlying J> Highek Beds. *{ Product i belonging to the giganteus-gvoup, 

 Dolomitic Beds. J i^and Athyridsof the ambigiia-group (Seminula). 



-^ Oolitic beds in the *> 

 eg quarry at the foot of 

 >o the Gully. 



1—1 . 



"5 Beds between the 

 J Gully & the Black- 

 "^ Rock Quarry. 



Group C. 



f Marked by the great abundance of Orthotetes 

 ! {Streptorhynchus) crenistria, Chonetes papi- 

 lionacea, and Ch. aff. comoides. In these beds 

 ^Spirifer aff. laminosus reaches its maximum. 



3 

 o 

 ,0 



Upper third of 



the Black-Rock 



Quarry. 



(~ Marked by the abundance of a Zaphrentid 

 Group B, •{ of the cylhidrica - type {Campophyllum = 



J resting immediately {^Zaphrentis cylhidrica oi Edw. & Haime). 1 

 upon or forming the 



^ p _ a ( Containing cornute Zaphrentids in great 



) ( abundance. 



Lower and middle 



thirds of the Black - 



Rock Quarry. 



> Lower Beds. 



J 



Marked by the rarity of Zaphrentids and by 



the gradual increase downward of Spirifers of 



the bisulcatus - group and of the ^rZaier-type 



<j {Martinia) : Athyrids of the Boyssii-type 



I (Cleiothyris) : Orthids of the Michelini- and 



i resupinata -types, Leptcena analoga, and Pro- 



[jhictus of the punctatus- and Martini-types. 



As will be seen by the sequel, the volcanic group lies approximately 

 on the horizon of Group B, a position which accords with that 

 assigned to the Middle-Hope and Spring-Cove lava by one of us — 

 that is to say, somewhat anterior in time to the Gully oolite. 



(1) At Middle Hope, Woodspring. 



The beds below the volcanic series, which are well displayed on 

 the coast-line, unquestionably belong to Group A, and contain 

 cornute Zaphrentids in great abundance. Mr. Yaughan has identi- 

 fied Zaphrentis Phillipsi, M.-Edw., Z. aff. Ennishilleni, M.-Edw., 

 Z. aff. Griffithi, M.-Edw., and Z. sp. nov. ; Michelinia, sp., Leptcena 

 analog a, Phill., Orthis Michelini, L'Eveille, Productus punctatus var. 

 elegans, M'Coy. The lower ashy beds are probably in Group B. On 

 the southern coast of the peninsula that terminates in Swallow Cliff 

 the Chonetes and Streptorhynchus characteristic of Group C occur ; 

 and similar beds may be found 150 feet above the more easterly 

 exposure of the tuffs. 



1 [Mr. A. Vaughan has more recently, in Proc. Bristol Nat. Soc. vol. x, pt. ii, 

 p. 102, revived M'Coy's genus Caninia, to cover the Zaphrentid-group which 

 is typified by Campophyllum cylindricum. — March 14th, 1904.] 



