ON THE LINGULA-FLAGS OF SOUTH WALES. 283 



these, in ascending order, lie the Grey flag with black bands, and the true 

 black beds (5 b), all well marked, and easily traced through their transitional 

 states into one another. The passage, moreover, is quite perfect. The upper 

 part of this section contains a thick bed or two of trap, — a circumstance com- 

 mon throughout the Lingula-flags in this district, as also occasionally in the 

 Upper Grey series of the Lower Cambrian, though I have never seen it occur 

 lower down. Mr. Salter has found it abundantly in the same beds in North 

 Wales. 



The 3rd, or Cradle Bock section, is a continuation of the second. The first 

 beds in this section are the thick sandstone ones which terminated section 2; 

 and upon these we have thin alternating beds of sandstone and shale of a 

 dark grey colour, fossiliferous, and occupying a thickness of about 250 ft. ; 

 next, a series of beds still dipping in the same direction for about 450 ft., and 

 composed of grey flaggy sandstone in thin beds, alternating at first with dark 

 grey or black shale, and afterwards -with yellowish shale. These last are 

 evidently the base of the Middle Lingula-flags. After this the beds curve into 

 a synclinal, which is again repeated about 600 ft. further on, so that but a 

 portion only of the Middle Lingula series is in consequence exposed here. 

 The general section thus sketched includes about 3000 ft. of conformable 

 strata, and may well be looked upon as the typical section. Several other 

 sections are also exposed inland, and along the coast, but in no case do we 

 find one so continuous or uninterrupted by faults. Again, all others that I 

 have examined, and which I may say include all the chief Cambrian masses 

 exposed in N.W. Pembrokeshire, tend in every case to prove the facts exhi- 

 bited clearly in this one. In most cases I have found the lithological charac- 

 ters of the beds, the thicknesses of the various series, and the fossils, when 

 present, to tally in every particular with this section. 



In section 2, or that of the east side of Porth-y-rhaw Creek, we meet with 

 all the principal fossil types. By means of a fault, the purple-stained beds 

 (4) are immediately followed by a set of beds, excepting in colour, appa- 

 rently identical with them, hard Grey grit (5 a) in thick compact beds, which, 

 as in the first section named, appear to be the top of the Lower Cambrian. 

 In these beds, and within a few feet of true purple beds, I found a new 

 Parado.rides, now named P.Aurora ; associated with it a new Conocori^he, of 

 large size ; a new TJieca, a LinguleUa, an Obolella, and fragments of Agnostus 

 and JIurodiscus. Unfortunately the first two are very fragmentary as yet, 

 but there is quite enough to pronounce them new ; and the Paradoxides is a 

 very peculiar species. Fragments of these lowest fossils are also found in the 

 creek to the west of Porth-y-rhaw, and through which I have taken section 1 ; 

 and at two or three other places, where they hold exactly the same relation 

 to the underlying purple beds, and to the series above. Though the purple 

 band series have not yet yielded any definite traces of these higher forms of 

 fossils, we arc scarcely, I think, warranted in looking upon that as proof of 

 their absence ; neither is it, I think, likely that so rich, though limited, a 

 fauna should come so suddenly into existence. About half a dozen only of 

 the lowest beds are distinctly fossiliferous, the succeeding 150 ft. having 

 yielded scarcely any traces as yet, though we may expect to find them. 



These last beds are much lighter in colour, being a grey grit, and having 

 only a few narrow dark bands. Rather abruptly the beds now become darker 

 in colour and of a finer grain,— a dark-grey flag. In these we meet with 

 Parad. Hiclcsii, not a new species, but one described already as P. Forchham- 

 meri, from some unknown locality in North Wales, according to the testimony 

 of my colleague, Mr. Salter, who has been trying for the last twenty years to 



