The interglacial period of marine depression in Britain is represented in Switzerland by the lignite beds of Dürnten, Utznach, and Pfaffikon, the last of which rests upon and is covered by the boulder drift. The fossil remains from Dürnten, identified by Dr. Falconer and Prof. Rütimeyer, prove that two southern animals, _Elephas antiquus_ and _Rhinoceros megarhinus_, inhabited the district in the interval between the retreat of one set of glaciers and the advance of another. They probably migrated from the plains of Lombardy, where they abounded in the pleistocene age. _Europe invaded by Pleistocene Mammals before the Glacial Period._ What is the precise relation of the pleistocene mammals to these two periods of cold? Did they invade northern and central Europe during the first or the second, before or after, the marine submergence indicated by the “middle drift?” We might expect, _à priori_, that as the temperature became lowered, the northern mammalia would gradually invade the region occupied before by the pleiocene forms, and that the reindeer, the mammoth, and woolly rhinoceros would gradually supplant the southern _Rhinoceros Etruscus_ and _Elephas meridionalis_. Traces of such an occupation would necessarily be very rare, since they would be exposed to the grinding action both of the advancing glacial sheet, and subsequently to that of the waves on the littoral zone during the depression and re-elevation of the land. At the time also that the greater part of Great Britain was buried under an ice-sheet, it could not have been occupied by animals, although they may have been, and most probably were, living in the districts farther to the south, which were not covered by ice. The labours, however, of Dr. Bryce, Prof. Archibald Geikie, and others prove that one at least of the characteristic pleistocene mammalia--the mammoth--lived in Scotland along with the reindeer before the deposit of the lower boulder-clay; while Mr. Jamieson has pointed out that it could not have occupied that area at the same time as the ice, and therefore must be referred to a still earlier date.[266] The teeth and bones discovered in the ancient land surface at Selsea, under the boulder drift, also very probably indicate that the mammoth lived in Sussex before the glacial submergence, although they were never admitted by Dr. Falconer to be of the same age as the remains of _Elephas antiquus_ from the same preglacial horizon. The animal also occurs in the preglacial forest-bed of Norfolk and Suffolk. On a careful examination of the whole evidence, I am compelled to believe, with Mr. Godwin-Austen and Prof. Phillips, that the _à priori_ belief that the pleistocene mammalia occupied Great Britain before the period of the ice-sheet and submergence is fully borne out by the few incontestable proofs that have been brought forward of the remains being found in preglacial deposits. And the scanty evidence on the point is just what might be expected from the