77 



fully executed, I have still sufficient recollection of it to admire 

 the beauty of the new delineations. If 1 may be allowed to sug- 

 gest a parallel between it and districts which I have more mi- 

 nutely described, I am greatly mistaken if North Pembroke does 

 not present phsenomena almost comyjletelj^ analogous to those of the 

 mineralized Lower Silurian rocks north of Builth in Radnor- 

 shire, and at Cornden and Shelve in Shropshire, where numerous 

 lines of contemporaneous trap alternate with Llandeilo flags and 

 Caradoc sandstone, and where the strata on the flanks of erup- 

 tive rocks are the seats of lead and copper ores, tlie sandstones being 

 often converted into quartz rocks (Caradoc, Stiper Stones, Wrekin, 

 &c. &c.). Combining the evidence of these tracts with those laid 

 open by the extensive transverse sections which I formei'ly made in 

 Montgomeryshire, in the north-Avestern parts of the Silurian region, 

 where the masses have been shown to roll over in great undulations 

 from S.E. to N.W., I am fully prepared to admit the existence of a 

 similar configuration in North Pembroke, West Caermarthenshire 

 and Cardiganshire, districts with which I Avas very imperfectly ac- 

 quainted, and where the aspect of rocks is at first sight, it must be 

 admitted, very forbidding to those who search after fossil evidences. 

 The greater, however, the diflficulty, th-e greater is the merit of those 

 who have solved the problem, and have thus established in parts 

 of South Wales the precise relations of what were previously con- 

 sidered to be anomalous masses. The result of this Survey, up to 

 the present moment, is, that in one small part only of North Pem- 

 broke is there any development of rock older than the strata con- 

 taining Lower Silurian fossils, and this occurs in the promontory of 

 St. David's, with which I am familiar : this rock, I can confidently 

 say,is mineralogically undistinguishable from the close-grained purple 

 greywacke of the Longraynd and Haughmond Hill in Shropshire; 

 and in both these localities it has hitherto been found as void of 

 fossils as in the similar rocks of the Lammermuir Hills in the South 

 of Scotland. 



In the south-eastern parts of the Silurian region, to \vhich the 

 Ordnance Geological Survey has also extended its labours, the ac- 

 curacy of the chief lines which had been laid down, whether in 

 May Hill, Usk, Woolhope, and the Malvern Hills, has been con- 

 firmed ; and, under the vigilant eye of Mr. Phillips, some new spe- 

 cies have been added to the former lists, both in the Lower and in 

 the Upper Silurian rocks. Among the latter the Pentamervs Knightii 

 has been found in a new locality, in the southern prolongation of 

 the axis of Woolhope, thus showing how persistently the place of 

 the Aymestry limestone is maintained ; whilst a species of that re- 

 markable shell, the Pleurorhynchus, has been detected in true Wen- 

 lock limestone. 



In relation to the west flank of the Malvern Hills, Mr. Phillips 

 has, by very close researches, come to an important conclusion. 

 Certain specimens of a peculiar conglomerate or breccia having 

 been found by his sister Miss Phillips, in which the Pentamerus 

 loEvis and other Caradoc fossils are associated with fi'agments of 



