part 2] THE YALENTIAIS^ SERIES. 163 



probably correspond in point of time to the greater part of the 

 Dailly Stage. Moreover, the close similarity between the fauna of 

 the basal members of the Uzmaston Group and the Camregan 

 Beds of Girvan indicates that the Millin Stage descends to the 

 base of the Upper Yalentian. 



The Rosemarket Stage. — The relations of the E-osemarket to 

 the Millin Stage and to the Wenlock rocks is unknown. The 

 rocks occur in different areas, and the lithological and faunal facies 

 are entirely different. The stage is distinguished b}" the abund- 

 ance of JPentamerus ohlongiis, which occurs in the Upper Yalentian 

 of Scotland in the Camregan, Penkill, and Bargany Gi'oups. 

 Moreover, the discovery of a CJimacograptus in beds considerably 

 above the base suggests that the stage may descend as low as the 

 base of the Upper Yalentian, and may, therefore, be actually con- 

 temporaneous Avith the totally different development of the Millin 

 Stage near Haverfordwest. The Eosemarket Stage can be con- 

 sidered most naturally with the well-known littoral facies Avhich is 

 developed in the Caradoc and other districts. 



VI. The LlajS'dotert Disteict. 



In this district three divisions have long been known, as the 

 result of Aveline's Avork between 1855 and 1857. The classification 

 is as folloAVs : — 



' Tarannon Shales ' ; pvirple and green shales. 

 Upper Llandovery ; sandstones with Pentameriis ohlongvs. 

 Lower Llandovery ; sandstones and mudstones with various species of 

 ' Pentamerus.' 



The re-examination of the area upon which I am engaged has 

 not, so far, resulted in the solution of all its problems ; but the 

 general succession can be stated. 



The Lower Llandovery consists of a lower division of relatively 

 barren mudstones and shales, with a basal group of sandstones and 

 conglomerates, and an upper division of fossiliferous sandy mud- 

 stones with thin sandstones. The only part of the formation that 

 is represented in museums is this upper subdivision, and from it 

 were obtained the type-specimens of some Avell-known Llandovery 

 species such as 'Atrypa'' {SfricMandinia') lens and ' Atrypa"^ 

 {SarrandeUa) iindata. The lithological succession is, up to a 

 point, remarkabl}^ like that of the Haverford Stage of Haverford- 

 west. 



The brachiopod fauna of the upper division is almost identical 

 with that of the Gasworks Mudstones, and like it is characterized 

 by abundance of FJecfamhonites dapUcatus, the type-specimen of 

 which was collected by Murchison from these beds. From them 

 also is derived one of the figured specimens of Barrandella 

 U7idata, with which the form that occurs so abundantly at Haver- 

 fordwest and at Girvan in the Mulloch-Hill and Saugh-Hill 

 Groups may be compared. The other figured specimens were 

 derived from a different localit}^ but apparently from the same 



