118 Mr. Weaver on the Older Stratified 



age ; as to their being in fact both referable to an epoch ante- 

 cedent to that of the Old Red Sandstone formation, and in 

 nowise connected with the latter as terms of the same series. 



tilestone appears to be confined to the Western flank of the Old Red Sand- 

 stone, serving as a base to the cornstone division : for on the Eastern side, 

 in the instances cited of flagstones between Mathon and Ledbury, and at 

 the N.E. suburb of Ledbury, it is not mentioned that these flagstones con- 

 tain there any fossils ; and hence they may prove to be n^ere modifica- 

 tions of Old Red Sandstone in that quarter. The continuity of the fossili- 

 ferous tilestone through the field, therefore, does not appear to be proved. 

 The observations made in the Clytha hills N. of Usk,' (pp. 438,' 4.39,) 

 seem to me to relate merely to modifications of the upper Ludlow beds ; 

 a simple change of colour from gray to red being quite unimportant. 



Analogy thus pointing to the Silurian system rather than to the Old Red 

 sandstone, is it venturing too far to suggest that the fossiliferous tilestone 

 might iiave been more appropriately included in the Silurian system ? For, 

 entering more into particulars, let it be considered that of the twenty- 

 seven species of shells enumerated as being found in the fossiliferous tile- 

 stone, seven species are marked as occurring in the upper Ludlow rock 

 also (figured in PI. 3, 5, and 19, and described in pp. 602 — 604. See also 

 p. 183.) And to this statement I may add, (although I have not my Tort- 

 worth fossils lying before nie, so as to speak with precision in all the cases) 

 I recognise several that are common in that Silurian district, especially at 

 Long's Quarry in Charfield Green, which quarter is designated by Mr. 

 Murchison as Caradoc sandstone. And with respect to the remains of 

 fish, which occur more particularly in the cornstone division, and to a less 

 extent in the tilestone, it may be observed that, while some species are 

 peculiar to each of those divisions, " the Ichthyodorulites of the Old Red 

 Sandstone belong to distinct species of the genera Onc/ms and Ctcnacan- 

 thus ; but some species of these genera exist in your Carboniferous, Old 

 Red, and Silurian systems," (p. 596. Observation of Mr. Agassiz to Mr. 

 Murchison). The most marked distinction therefore consists in the shells 

 found in the tilestone division. 



From the preceding considerations the question arises, whether it would 

 not be a more natural view to consider the Old Red Sandstone formation, 

 properly so called, as restricted to that great mass which is composed of 

 Mr. Murchison's upper and central divisions, preserving thus the analogy 

 with other countries; the upper division, the conglomerate and sandstone, 

 being wholly non-fossiliferous (with the exception, as before stated, of a 

 few vegetable remains), and the under division, the cornstone and marl, 

 distinguished by the presence of the remains of fishes and the absence of 

 shells. With respect to the fish remains in the cornstone, the analogy 

 also holding good in Scotland and the Orkney Isles, it may become an 

 interesting object of research to ascertain, whether they occur also in the 

 marly clays of the Old Red Sandstone formation in Ireland. 



Considered in this point of view, and thus restricted, the Old Red Sand- 

 stone formation may be considered, as it has hitherto been, as the first 

 member of the carboniferous series, which, being most commonly uncon- 

 formable, and forming a break with the Older Stratified Rocks, marks the 

 commencement of a new epoch; and serving as a base to the succeeding 

 deposits of the carboniferous limestone and coal-measures, these three 

 are often interstratified one with the other in the order of succession. 

 They thus constitute together a natural group, which, in conformity with 

 the view hitherto entertained, has been very appropriately designated the 



