Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/686

 but in their place large flints, a few bits of hardened clay, and bones and teeth of Cervus*, Equus, and also Trogontherium. Further, it is to be remarked that the teeth of Mastodon found in the Norfolk stone- bed are not so thoroughly mineralized and so heavy as those from the Suffolk bone-bed, whilst the bones which occur in that bed are certainly by no means so heavy as those from Suffolk. The Norfolk stone-bed rests on chalk, the Suffolk bone-bed on London clay. Immediately above the Norfolk stone-bed is the Norfolk Crag, with its nearly recent subarctic molluscan fauna. Immediately above the Suffolk bone-bed is the Coralline Crag with its many extinct and tropical forms, or, where this is not present, the lower and older part of the Red Crag, or, in some places, higher sandy beds. Both stone-bed and bone-bed have, in places, been much disturbed and broken up by the sea which deposited the strata above them. Taking these facts into consideration, it is impossible to assign a simple community of origin and date to these two beds. The Suffolk bone- bed has evidently derived its contents from sources which were not accessible to the Norfolk deposit ; such are the London clay and the destroyed Diestien beds. But what of the terrestrial Mammalia†? Was the Mastodon of the Norfolk stone-bed coeval with the Mastodon of the Suffolk bone-bed ? If it were, we must suppose that the Rhinoceros Schleiermacheri, Hipparion, &c. of the Suffolk bed belong to an earlier age, and were not contemporary with the Mastodon arvernensis found with them, since in the Norfolk area these other forms are not present with the Mastodon. Also we must assume that the Elephas meridionalis, Equus, and Trogontherium of the Norfolk stone-bed belong to a later period than the Mastodon arvernensis found with them, since it may be positively asserted that Elephas does not occur in the Suffolk bone-bed. Again, there is no doubt that the terrestrial mammalian fauna (not considering here the well-identified Eocene species of Coryphodon and Hyracotherium which occur) of the Suffolk bone-bed is earlier in date than the Coralline Crag, and, perhaps, earlier than the Diestien beds which preceded that Crag, since I have obtained the tooth of a Trilophodont Mastodon from the bone-bed, with the Diestien sandstone-matrix enveloping it. This cannot be said of the Mammals occurring at the base of the Norwich Crag. All that we can assert of them is that they belong to an earlier date than the newer Crag ; they are possibly not so old as the Coralline or even the earlier part of the Bed Crag. The condition of the Mastodon teeth from the Norfolk stone-bed is decidedly one of less mineralization than that of those from the Suffolk bed, and none of them bear marks of the same extensive water-wearage which are apparent on very many from Suffolk. Moreover, the Rev. John Gunn obtained very fair evidence of the occurrence of a nearly complete skeleton of Mastodon arver-


 * Mr. Boyd Dawkins, F.R.S., considers that there are species of Cervus common to the Suffolk bone-bed and the Norfolk stone-bed.

† In using the term " terrestrial mammalia of the Suffolk bone-bed " I wish to be understood as excluding the derived Eocene. Coryphodonts and Hyracotherium. These, however, are the only Eocene forms which have occurred.