This gives a slight increase in the proportion of northern spe- cies in the Norwich Crag, while the proportion of southern species shows a greater decrease, hut not more than might be dependent on local coast conditions. The relative proportion of total British species in the Red and Norwich Crags respectively is as close as 67 : 69, while the total northern forms show as 80 : 105, and southern forms 150 : 104. Or, taking the species not now found living in the British seas, their relative distribution in the three Crags is as under : —
Species now restricted to
Total living species. Northern seas. Southern seas.
Norwich Crag 130 19 11
Red Crag 216 23 32
Coralline Crag 264 14 65
So that while the relative number of British species, as well as of the extinct species, remains nearly uniform, there is a considerable decrease of southern and some increase of northern species in the Norfolk area.
The relation of the two crags as shown by the Mammalian remains is less conclusive ; but the differences are no greater than we might expect from the evidently different relations of the land to the water in the two areas. The same Mastodon*, Horse, Hyaena, and Felis occur in both ; and there is strong reason to believe that the Elephant (meridionalis ?) is likewise found in the Red Crag. A Bear (arvernensis), and a Deer (megaceros), though not found in the Norwich area, are found in the Suffolk Red Crag, and pass into the Forest-bed, and must therefore have existed in the Norwich- Crag period.
After carefully weighing all these considerations, I must confess that, as I see no sufficient reason for regarding any of the Norwich- Crag Mammalia as extraneous fossils, I now cannot but look upon all species common to the two Crag areas, together with those species which, though not found in both Crag areas, are still found in one, and occur again in the later-deposited Forest-bed, as really contemporaneous fossils proper to the Red and Norwich-Crag series. This view is in the main in accordance with that arrived at by Dr. Falconer, upon the evidence of the contemporaneous continental Pliocene fauna.
The Forest- and Elephant-bed inaugurate a condition of things materially different from that prevailing during the Crag period. A number of new Mammalia make their appearance, including the Elephas antiquus and var. priscus in numbers, two new species of Rhinoceros, a Hippopotamus, two Bears, together with species of Horse and Ox, and some small rodents of existing species. But the marked feature of the period consists in the number and variety of the Deer, no fewer than six species, several of them of very peculiar
- As the occurrence of the nearly entire skeleton of the Mastodon at Horstead
shows that it lived in the Norfolk Crag area, I do not think that it can be looked upon as extraneous to the Red Crag.
