29 



faces of the joints, where we find lines of cavit.es formed by h 

 sohxtion of the calceareous matter in the fossiliferous layer. -the 

 very character on ^vhich SiR E. Murchison lays stress as mdicaung 

 the Aymestry Limestone. This honeycomb formation may be seen 

 xnore Or less, nearly as far as the turn of the sloping walk leadrng 

 up Whitcliff from the Xew Bridge. ,,11 



Does it not then seem clear that the classification should be 

 altered, so as to include all beds in which these fossils and honey^ 

 comb markings are found, in the Aymestry 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 

 Jl 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 Su--yor at that 

 time being unaware of the faults, and fancying the Whitcliff bed 

 all of the same nature, because they had nearly the same dip, and 

 aU contained Chonetes lata, Rhynchonellu nucula, Orthonota 

 amvodalina, and other common Upper Ludlow forms ; but these 

 forms also nm do..r to the bottom of the Lower Ludlow. ^\ hen, 

 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. StiU I am 

 far from assuming that we shall always be able to say whether a 

 certain rock is Upper Ludlow or Lower Ludlow, because m 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 fossd, we shall be stdl 

 in the dark. It will, however, answer weU 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 Aymestry Limestone and Lower Lud- 

 low • at the general prevalence of calcareous beds in both formations 



