558 Mr. Maclauchlan's Notes on Fossils collected in Pembrokeshire. 



at Solfach, to the south-east, and Porthlliskey, to the south-west of St. David's ; 

 at the latter village the dip becomes westward, and continues changing to Whitesand 

 Bay, where it assumes a northerly inclination, as may be observed at St. Law- 

 rence, thirteen miles east of St. David's Head, Leweston, three miles south of St. 

 Lawrence, Camrose, and Long Ford, about two and a half miles south of Llan- 

 dysilio ; the line is broken at Roche, five miles south-west of St. Lawrence, and 

 at Leweston by the intrusive trap. 



Graptolites were found at Robleston, in the parish of Camrose, in calcareous 

 shales, near their junction with the trap of Plumstone. 



Resuming the section at Llys-y-fran and proceeding towards Dinas Head, roof- 

 ing-slates alternate with trap, decomposed on the surface, and masses of apparently 

 intrusive greenstone are bkewise visible : these traps and slates have been traced 

 for miles to the east and west of the line, the schists dipping with remarkable 

 uniformity to the north. This would lead to the supposition that the trap was 

 contemporary with the slates, but the cursory view obtained on the surface pre- 

 vents any certain conclusion being formed. 



The slates at Abereiddy Bay (sect. fig. 1.) contain Graptolites, as observed by 

 Professor Sedgwick; and two species appear, from Mr. Lonsdale's examination, to 

 be identical with the Graptolithus Murchisonii diud foliaceus of the Llandeilo Flags. 

 In the same bay are found numerous specimens of an Euomphalus, which bear 

 some resemblance to one of the specimens represented by fig. 13. Plate XXH. of 

 the Silurian System; also specimens of a Lingula, but distinct from the Llandeilo 

 Flags, species figured by Mr. Murchison. 



The beds, which are worked for roofing-slate at Abereiddy Bay, are inclined 

 highly to the north, the line of bearing being from north-east to south-west ; and 

 though they differ in mineral character, as well as dip, from the general inclination 

 of the Llandeilo Flags, yet this difference may have been produced by the action 

 of the trap, which intersects them in a north-east and south-west direction, and 

 between Abereiddy and St. David's occupies nearly the whole surface. 



Overlying these slates, to the north, but with many beds of trap, slates, and 

 sandstones between them, having the prevailing northerly dip, we find the conglo- 

 merate of Dinas Head (fig. 1.), Newport Bay, and Trewiddel, near Cardigan, com- 

 posed of fragments of various rocks, cemented by a grit of trappean aspect, and 

 resembling certain conglomerates described by Mr. Murchison as occurring in the 

 Caradoc sandstone. 



The organic remains hitherto obtained from these beds are not very satisfactory, 

 but the most prevailing fossil is the cast of a crinoidal stem, composed of numerous 

 thin joints with interspaces at irregular distances ; the best specimen of which, 

 procured at Trewiddel, near Cardigan, Mr. Lonsdale considers analogous to speci- 



