In 1885 Dr. C. A. White, F.C.G.S., Palæontologist to the U.S. Geological Survey, supplied me with some of the siliceous residue of a limestone belonging to the freshwater Jurassic Atlantosaurus-beds in Colorado, from which several casts of small Ostracoda were figured and described in the GEOLOGICAL MAGAZINE, Dec. III. Vol. III. April, 1886, pp. 145–8, Pl. IV. Since that time Dr. White has kindly sent me somewhat similar material, obtained in like manner, by dissolving in dilute acid pieces of an impure limestone, which lies at the base of the Upper Cretaceous Series, from Cokeville, a hamlet in South-Western Wyoming, and belongs to the Bear-River Formation. The Ostracoda selected are figured in Plate XV. Figs. 1–9, 11–13, and 15. These casts represent the whole carapace in many if not all instances.

The genus Tapirus of all the recent Ungulata, is the most discontinuous in its distribution over the Earth's surface. Wallace, in his great work on the “Geographical distribution of Animals,” in referring to extinct Tapirs, remarks: “the singular distribution of the living species is thus explained, since we sea that they are an old world group, which only entered the American continent at a comparatively recent epoch.” He reaches this conclusion by the fact that at the time his work was written (1876) the only known remains of the Tapiridse in America were from the Post-Pliocene deposits.

In a recent article on the Pre-Cambrian Rocks of the British Isles in the Journal of Geology, vol. i., No. 1, Sir Archibald Geikie makes the following statement: “There cannot, I think, be now any doubt that small tracts of gneiss, quite comparable in lithological character to portions of the Lewisian rocks of the North-West of Scotland, rise to the surface in a few places in England and Wales. In the heart of Anglesey, for example, a tract of such rocks presents some striking external or scenic resemblance to the characteristic types of ground where the oldest gneiss forms the surface in Scotland and the West of Ireland.” To those who have followed the controversy which has been going on for nearly thirty years between the chiefs of the British Geological Survey and some geologists who have been working amongst the rocks in Wales, the importance of the above admission will be readily apparent; but as it is possible that some may be unable to realize what such an admission means in showing geological progress in unravelling the history of the older rocks in Wales during the past thirty years, a brief summary of the results obtained may possibly be considered useful.

In a spirited treatise on the ‘Origin of our Animal World’ Prof. L. Rütimeyer, in the year 1867, described the geological development and distribution of the mammalia, and the relationship of the different faunas of the past with each other and with that now existing. Although, since the appearance of that masterly sketch the palæontological material has been, at least, doubled through new discoveries in Europe and more especially in North and South America, this unexpected increase has in most instances only served as a confirmation of the views which Rutimeyer advanced on more limited experience. At present, Africa forms the only great gap in our knowledge of the fossil mammalia; all the remaining parts of the world can show materials more or less abundantly, from which the course followed by the mammalia in their geological development can be traced with approximate certainty.