810 Prof. Sedgwick on the May Hill Sandstone, 



been made in a bed of shale, with innumerable specimens of 

 TVinucleus, 



5. " Still further up the river followed the well-known Caradoc 

 beds of Horderley/' 



In the above section the highest beds are undoubted Wenlock 

 shale. The lower beds (groups 3, 4 and 5) are undoubted Cam- 

 brian (one of the upper sandstones of the Bala group). The 

 intermediate, or May Hill group, is lost. 



There is therefore no contradiction in the section to the views 

 given in my previous paper of Nov. 3, 1852. We have no alter- 

 nation of true Cambrian and true Silurian types; and I now 

 believe that the Trinucleus shale laid bare by an excavation a 

 little above Longville Bridge, was (by an error in my notes in 

 1842) placed a little above Stretford Bridge. This conclusion 

 I should have come to sooner, had I dared to coax my notes into 

 an agreement with my subsequent views. 



IV. Sections near Shineton through a part of the Caradoc terrace, 

 a few miles to the north-west of Wenlock. 



What I had first thought the most important object of our 

 excursion was to examine the whole Caradoc terrace between the 

 Onny and the Severn, in order that we might learn whether 

 there existed in that district any unequivocal traces of the May 

 Hill sandstone interposed between the true Caradoc beds and 

 the Wenlock shale. I thought it probable when my former 

 paper was written (Nov. 1852), that here (as in the lower part of 

 Glyn Ceiriog) the Wenlock shale might hy an overlap have been 

 brought immediately into contact with the true Caradoc group. 

 But before we commenced our excursion, we learnt from Mr. 

 Salter, who had just before visited the country near Wenlock, 

 that the previous conjecture was erroneous, and that there did 

 exist at Shineton and other places along the Caradoc terrace, a 

 series of beds which represented the May Hill sandstone. He 

 gave us his best localities, and a short list of the fossils he had 

 collected from them ; and he added his conviction, that these 

 so-called May Hill beds at the base of the Wenlock shale were 

 unconformable to the contiguous parts of the trite Caradoc 

 sandstone. 



While I was still unable to take the field. Prof. M'Coy not 

 only traversed the north-eastern end of the Caradoc terrace, but 

 completely verified the previous observations of Mr. Salter ; and 

 I will give the result of his observations in his own words. 



(1.) " On the road-side, close to Shineton Church, are olive- 

 coloured shales which dip about 35° E. of south, and at about 

 30°. They were found to contain the following fossils : — 



Agnostus pisiformis (as at Llandeilo, &c.) in great abundance. 



