1. R. megarhinus, Christol, being the original and typical R. leptorhinus of Cuvier, founded on Cortesi's Monte Zago cranium, and the ONLY Pliocene, or Pleistocene European species, that had not a nasal septum.--Gray's Thurrock, etc. 2. R. hemitoechus, Falconer, in which the ossification of the septum dividing the nostrils is incomplete in the middle, besides other cranial and dental characters distinguishing it from R. tichorhinus, accompanies Elephas antiquus in most of the oldest British bone-caves, such as Kirkdale, Cefn, Durdham Down, Minchin Hole, and other Gower caverns--also found at Clacton, in Essex, and in Northamptonshire. 3. R. etruscus, Falconer, a comparatively slight and slender form, also with an incomplete bony septum,* occurs deep in the Val d'Arno deposits, and in the "Forest bed," and superimposed blue clays, with lignite, of the Norfolk coast, but nowhere as yet found in the ossiferous caves in Britain. (* Falconer, "Quarterly Journal of the Geological Society" volume 15 1859 page 602.) Dr. Falconer announced in 1860 his opinion that the filling up of the Gower caves in South Wales took place after the deposition of the marine boulder clay,* an opinion in harmony with what we have since learnt from the section of the gravels near Bedford, given above (Figure 23), where a fauna corresponding to that of the Welsh caves characterises the ancient alluvium, and is shown to be clearly post-glacial, in the sense of being posterior in date to the boulder-clay of the midland counties. (* Ibid. volume 16 1860 page 491.) In the same sense the late Edward Forbes declared, in 1846, his conviction that not only the Cervus megaceros, but also the mammoth and other extinct pachyderms and carnivora, had lived in Britain in post-glacial times.* (* "Memoir of the Geological Survey" pages 394 to 397.) The Gower caves in general have their floors strewed over with sand, containing marine shells, all of living species; and there are raised beaches on the adjoining coast, and other geological signs of great alteration in the relative level of land and sea, since that country was inhabited by the extinct mammalia, some of which, as we have seen, were certainly coeval with Man. OSSIFEROUS CAVES IN THE NORTH OF SICILY.