Note 254 — Front matter (continued 4)

These first mammals, which were exceedingly small, are supposed by most naturalists to have been Marsupials. They would appear presently to have become extinct, no traces of them having been found in the chalk, a formation so rich in other organic remains. As Professor Marsh tells us on this subject (Nature, September 27, 1877, p. 471):

"Of the existence of Mammals before the Trias we have no evidence, either in the New or the Old World, and it is a significant fact that at essentially the same horizon in each hemisphere similar low forms of Mammals make their appearance. Although only a few incomplete specimens have been discovered, they are characteristic and well preserved, and all are apparently marsupials; the lowest mammalian group known in America, living or fossil. The American Triassic mammals are known at present only from two small lower jaws, on which has been founded the genus Dromotherium, supposed to be related to the insect-eating Myrmecobius, now living in Australia. Although the fauna of Europe have yielded other similar mammals for the Oolite, America has as yet none of this class from that formation, while from the rocks of cretaceous age, no mammals are known in any part of the world."