276 PROCEEDINGS OF TIIE GEOLOGICAL SOCIETY. [Feb. 4, 



sponding beds in North Wales. On this point I hope to have an 

 opportunity of laying some particulars before the Society. My 

 object now is only to point out the locality and geological place of a 

 gigantic Trilobite long looked for in Britain, and lately, I must say 

 accidentally, found by me. I believed I was working at Solva Har- 

 bour, in Llandeilo flags*, but by good fortune I had landed instead in 

 a parallel creek a mile to the westward, at the junction of the red 

 and purple Cambrian grits with the Lingula-slates. 



Porth-rhaw is a small boat- creek, a mile S. of Whitchurch, on 

 the St. David's road. Black slates occur on both sides of it ; but on 

 the west side they pass into and rest upon the red and purple Cam- 

 brians ; on the east they form magnificent cliffs of vertical or highly 

 curved slates and flags. Sometimes these cliffs show sheets of rip- 

 pled rock 150 feet to the water's edge. Though much curved, the 

 general dip is to the east and south-east ; but I have not traced the 

 slates further in this direction than the Cradle Rock ; nor could I find 

 fossils except at one point, where they are in hundreds. This was 

 at Porth-rhaw, before mentioned, in the black vertical rocks on the 

 east side of the little creek. A boat may reach them easily ; but, 

 except at low water, it is not very easy to walk down to them. 



The fry of some large Trilobite first attracted my attention, and 

 then, by looking along the ledges, I found fragments (head, body- 

 rings, labrum), but none perfect, of the largest species of Paradox- 

 ides known — scarcely excepting the great P. Harlani, from near 

 Boston. Agnostus accompanied it as usual, being the smallest, as 

 Paradoxides is the largest, Trilobite of the Primordial zone. 



I shall describe the species (for it is new), with full figures, in a 

 forthcoming Decade of the Geological Survey ; and only now sub- 

 join a short diagnosis, and a reduced figure from a drawing by Mr. 

 C. R. Bone. 



Paradoxides Davidis, spec, no v. 



P. pedalis et ultra, maximus, glabella clavata, sidcis duobus solum perfectis. Oadi 

 submediani, parvi. Thorax axe fere ut pleura lato, hcec recta, apicibus recurvis, 

 nee abrupte flexis, sulco mediano valde obliquo marginem attingente. Cauda 

 lata. Labrum angulis externis biangulatis. 



Locality. — Lower Lingula-flags, Porth-rhaw, St. David's, Pem- 

 brokeshire (1862) ; also Solva Harbour, west side. 



There has been a single specimen of Paradoxides for a long time 

 in the Collection of the Geological Survey. It is a much smaller and 

 more slender species ; for P. Davidis is robust in all its parts, and 

 has a broad axis, like the Bohemian P. spinosus. The small species 

 in question t was found in 1ST. Wales by A. C. Selwyn, Esq., now 

 Director of the Geological Survey of Victoria ; but the exact locality 

 was never ascertained, nor could the species be again met with. I 

 recommend my North- Welsh friends (after one of whom, conspicuous 



* I have since found that the black Lingula-flags, with Paradoxides, extend 

 to Solva Harbour. 



t P. Forchhammeri (see ' Siluria,' 2nd edit. p. 45, fig. 5, 2). 



