part 2] THE YALENTIAiS^ SEEIES. 169 



At a higher level Splrlfer elevatus makes its appearance in 

 association with Horiostoma sculptum and Strophomenids, the 

 whole being strongly suggestive of a Wenlock age. These forms 

 are associated, however, with rare examples of Sarrandella glohosa 

 and SU'icMandinia lirata. Palwocycliis no longer occm-s ; but 

 in Marloes Bay it is found in association with Spirifer elevatus. 

 This horizon may be taken to indicate the overlap of the Valentian 

 and the Wenlock fauna, and (together with the underlying StricJc- 

 landinia Beds) may be correlated with the Woolhope Limestone 

 and the few feet of strata that immediatel}^ underlie it. Such a 

 correlation had already suggested itself to J. W. Salter and 

 Sir Henry De la Beche during their original survey of this coast. 



An intei-esting comparison ma}'' be made with the Tortworth ^ 

 area, where two ' trap-bands ' are intercalated among fossiliferous 

 calcareous sandstones. The brachiopod fauna includes the following 

 forms: — Coelospira liemisplierica^ Atrypa reticularis. Stropheo- 

 donta Goinpressa, Spirifer elevatus, Stricklandiuia lens. S. lirata, 

 and in addition I^alceoci/clus prceacutus and Horiostoma globosuyn 

 [zzz sculptum). The general similarity of this fauna to that of 

 the Wooltack-Marloes area at, and just below, the base of the 

 Wenlock Series is evident ; but in the Tortworth district forms 

 are associated together which in Pembrokeshire are more widely 

 spaced out. 



It is interesting to observe that the beds above the upper 'trap' 

 contain Palceocj/clus prceacutus in abundance, associated with 

 StricMandinia lirata., Spir if er elevatus, and Horiostoma glohosum 

 — an assemblage which is identical with that of Wooltack and 

 Marloes. Unfortunatelj^ the name lirata has been applied to 

 most ribbed forms of StricMandinia, and it is not known whether 

 the one recorded is the typical form. 



At Tortworth these occur with Stropheodonta compressa and 

 Coelospira hemisplierica, which in Pembrokeshire are restricted to 

 a lower horizon. On the otlier hand, Jferistina tumida and 

 Spirifer crisp)us, which are found with them at Tortworth, are 

 characteristic of the Wenlock in Pembrokeshire. 



The rocks between the two ' trap-bands ' contain Ccelospira 

 hemisplierica, Stroplieodonta compressa., StricJdandinia lirata, 

 together with S. lens. Spirifer crispus is also recorded, as well as 

 Horiostoma glohosiom. 



It is possible that onl}^ a small time-interval is represented by 

 the Tortworth rocks, and that they may be regarded as lying 

 wholly within the horizon of overlap between the Valentian and the 

 Wenlock : that is, the strata lying at the base of, and immediately 

 underneath, the Woolhope Limestone. 



These comparisons establish the fact that the rocks 

 of the shelly facies which have commonly been assigned 

 to the Upper Llandovery are equivalent generally to 

 those which may be proved to be of Gala or Upper 



1 C. Lloyd Morgan & S. H. Eeynolds, Q. J.G. S. vol. Ivii (1901) p. 267; 

 F. R. C. Reed & S. H. Reynolds, ibid. vol. Ixiv (1908) p. 512. 



