1871.] HAEKNESS AKD HICKS ST. DAVId's PROMONTOBT. 389 



seen on the E. side of the stream below Clegyr Bridge. These rocks 

 have a thickness of about 400 feet ; and on the N.i^.W. side of the 

 axis the greenish flaggy sandstones also occur, resting conformably 

 on the conglomerates. 



On the S.S.E. side of the ridge the greenish flaggy sandstones 

 have above them red shaly beds, agreeing in their inclination with 

 the strata on which they repose ; and these red shaly beds have 

 afforded the earliest traces of organic remains which have been 

 hitherto discovered in the St. David's promontory. These remains 

 consist of Lingula ferruginea, Salt., a form previously mentioned, 

 another and larger Lingulella, a Discina, and a new species of Le- 

 percUtia of considerable size, L. cambrensis, Hicks. 



These red shales occur on both sides of the quartziferous ridge. 

 They are seen on the N.^.W. side, in Eamsay Sound, where fossils 

 have also been obtained from them near Castell. A small frag- 

 ment of a Trilobite has likewise been met with in the red shales of 

 this locality ; but this fragment was not sufficiently distinct to allow 

 of the form being satisfactorily determined. 



On the S.S.E. side of the ridge the fossiliferous shales are seen 

 at Perth Clais Harbour ; and in this spot also fossils occur*. They 

 are likewise seen under the ruins of Nun's Chapel, at Ehosearry- 

 Ihuyd, and also at Caerfai and Mill. These red fossiliferous shales 

 have a thickness of about 50 feet. 



On the S.S.E. side of the axis, reposing conformably on the 

 fossiliferous red shales, purple sandstones having occasional green 

 bands associated in them occur, somewhat coarse in grain. These 

 purple sandstones are about 1000 feet thick ; and hitherto no fossils 

 have been obtained from them. These sandstones are now being 

 largely worked, the stone used in the restoration of the Cathedral 

 of St. David's being obtained from them. They afibrd large blocks, 

 which dress well. 



On the N.N.W. side of the axis the thick purple sandstones are 

 represented by deposits having more varied colours. On the E. side 

 of Ramsay Sound, where the fossiliferous red shales occur, these 

 are seen to be succeeded by greenish sandstones, upon which are 

 rocks reddish in colour passing upwards into a series of purple strata. 

 Greenish sandstones rest upon the purple strata ; and above these 

 are purple-coloured beds, having within them red layers. These 

 varied-coloured sandstones represent the thick purple sandstones on 

 the S.S.E. side of the axis ; and they are also almost unfossiliferous, 

 so far as present observations go. 



The thick purple sandstones of the S.S.E. side of the St. David's 

 promontory have superposed conformably upon them yellowish- and 

 grey-coloured sandstones and shales. In the lower portion of these 

 yellow- coloured rocks there have been found remains of a large and 

 new form of sponge, Protospongia major, Hicks. These strata, 

 which have some conglomerate beds associated with them, have 

 also afforded Trilobites, one of which appertains to a new genus, and 

 the other forms are new species. These are Plutonia SedgtvicJdi, 

 * Davidson on the Earliest British Brachiopoda, Geol. Mag. vol. v. p. 306. 



