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any bed I know of in the true Upper Ludlow, — but it contains abundantly 

 Strophomena filosa and depressa, Atrypa reticularis, and in the lower part Lingula 

 striata, Encrinicrus punctatus and variolaris, and Proetus Stokesii, all of which 

 belong emphatically to the Aymestry beds. None of these fossils, I believe, can 

 be found above this horizon, while they run through the Aymestry Limestone, 

 and at least to the bottom of the Lower Ludlow. 



Another indication of their nature occurs in the existence, in these beds over 

 the limestone, of the honeycomb structure of the faces of the joints, where we find 

 lines of cavities formed by the solution of the calcareous matter in the fossiliferous 

 layers, — the very character on which Sir R. Murchison lays stress as indicating 

 the Aymestry Limestone. This honeycomb formation may be seen more or less, 

 nearly as far as the turn of the sloping walk leading up Whitcliff from the New 

 Bridge. 



Does it not then seem clear that the classification should be altered, so as to 

 include all beds in which these fossils and honeycomb markings aie found in the 

 AjTnestry Limestone, and only refer those above them, which are destitute of 

 such forms, to the Upper Ludlow. The great advantage of this would be to 

 enable us to separate (wherever these fossils are found) the Upper Ludlow from 

 the Lower Ludlow, instead of having them confounded together in the maps by 

 the same colour, wherever the limestone happens to be absent. No doubt the 

 error arose from the Surveyor at that time being unawaure of the faults, and 

 fancying the Whitcliff beds all of the same nature, because they had nearly the 

 same dip, and all contained Chonetes lata, Rhynchonella nucula, Orthonota amygda- 

 lina, and other common Upper Ludlow forms ; but these forms also run down 

 to the bottom of the Lower Ludlow. When, however, the fossils of the beds I 

 am speaking of were classed with the Upper Ludlow, of course the discrimination 

 of the Lower Ludlow from the Upper Ludlow became impossible, except where 

 the limestone intervened — -which yet is often wanting. Still, I am far from 

 assuming that we shall always be able to say whether a certain rock is Upper 

 Ludlow or Lower Ludlow, because in the western parts of these beds, not only is 

 the limestone absent, but the fossils are very few in number, so that, unless we 

 by chance break open a characteristic Lower Ludlow fossil, we shall be still in the 

 dark. It will, however, answer well in many places ; and even if it did not, that 

 would be no reason why we should not endeavour to discriminate as much as 

 possible. 



The examination of this point has suggested to me the probability of another 

 alteration being required. Looking at the general identity of the fossils of the 

 A>Tnestry Limestone and Lower Ludlow ; at the general prevalence of calcareous 

 beds in both formations — only varying in thickness and frequency ; and at the 

 difficulty, if not impossibility, of pointing out, even in the best sections (such as 

 Mocktre), where one ends and the other begins ; will it not be better to merge 

 the one in the other, and to call the whole series Lower Ludlow ? 



We have lately seen a further confirmation of this view, in a quarry on the 

 west side of the old Mocktre road, where we find a bed of Pentamerus Knightii at 



