Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/688

 cene fauna and survived afterwards to bear a part in the Pliocene fauna, which is indicated by the Norfolk Elephas meridionalis. An objection to this is found in the absence of the Mastodon from the forest-bed, and from all association with E. meridionalis in localities north of the Val d'Arno.

3. The Mastodon arvernensis, certain species of Deer, and perhaps some other of the Mammalia, indicated by remains in parts of the Suffolk bone-bed, may be regarded as belonging to a later fauna than that to which the Trilophodont Mastodon (below described), the Rhinoceros Schleiermacheri, Tapirus prisons, and Hipparion belong. The M. arvernensis fauna may be supposed to have succeeded the R. Schleiermacheri fauna, and at the same time to have existed in Norfolk, extending to a period later, probably, than the Coralline Crag ; whilst, at an earlier epoch, the Miocene mammals left their remains in the Diestien sands, which preceded the Crag, as is proved by the tooth of a Trilophodont Mastodon before mentioned. The condition of some teeth of Mastodon arvernensis from Suffolk, with their fangs preserved, tends to favour this view. The absence of Elephas from Suffolk, and its association in small proportion with the Mastodon in the Norfolk stone-bed, may be accounted for by granting what has been found to be true for France, namely that Elephas meridinonalis did not coexist with Mastodon arvernensis. "We may suppose that the E. meridionalis and Trogontherium of the Norfolk stone-bed lived after Mastodon arvernensis had passed away, belonging to a distinct fauna-period, that of the E. meridionalis, fully represented in the forest-bed. Living on the lands which already contained remains of the Mastodon arvernensis in the silt of streams, in bogs, &c, these animals ultimately became associated with the past fauna in the Norfolk stone-bed. Thus we get three groups of animals or faunae, A, B, and C, associated by the breaking up of an old land surface. B left its remains in Suffolk, which already contained the remains of A, and in Norfolk, where A's remains did not exist ; C left its remains in Norfolk where B's remains existed, but not in Suffolk, which had already the remains of A and B. A is the R. Schleiermacheri group, B the M. arvernensis group, and C the E. meridionalis group of mammals.

The physical conditions indicated by the Diestien deposits in Suffolk, their absence from Norfolk, and the distribution of the later deposits, are apparently such as would favour the separation of the Norfolk and Suffolk areas as required in the above hypothesis.

Of the three hypotheses here offered I am inclined to the last, and though it is confessedly but a speculation, I submit that this question admits of a fair attempt at solution, and that we must not be content with the mere assertion that the bone-bed in Suffolk is a very heterogeneous assemblage of remains, and contains forms derived from the London clay as well as Mastodon. Hyracotherium and Coryphodon have only occurred altogether about six times in the nodules of clay from this bed ; it is manifestly absurd, therefore, to speak of the London clay or Eocene beds as contributing largely to the mammalian fauna of the Suffolk Crag.