During the past few months some papers on early amphibia and reptiles have reached me from America, Russia, and China. These have afforded me much pleasure as a change from my present unaccustomed work, and I therefore feel that I can usefully express my thanks to their authors by writing a criticai summary of their conclusions. And such a review is justified because collectively these papers add very greatly to our knowledge and understanding of the evolution of early Tetrapods. Reference will be made to a list of these papers at the end of this review. It is most convenient and logical to discuss firstly the individual animais and then their distribution in time.

Pleistocene deposits near Homa were first visited by Dr. F. Oswald (1914), who described the exposures at Kanjera. Dr. L. S. B. Leakey and his colleagues of the 1931–2 East African Archaeological Expedition located human remains while collecting the fauna of the beds, and the importance of this discovery led to resumption of work on the area by the 1934–5 expedition to which the writer acted as geologist, and to a special study of the geology of the area and provenance of the human remains, for which Professor P. G. H. Boswell joined the expedition at Dr. Leakey's invitation, his visit being facilitated by the Royal Society. Mr. E. J. Wayland, of the Uganda Geological Survey, also spent a short period with the expedition before Professor BoswelPs return. It was a sad disappointment to ali concerned that the early date of the human remains could not be established with certainty (Boswell, 1935), but in tne present note it is proposed to describe the geology of the deposits, which is itself of considerable interest.

A number of test bores were sunk for Swansea Corporation in 1931 during the investigation of a site. Some samples were obtained by Professor O. T. Jones, F.R.S., from a line of borings east of Swansea, which trended north-east from the eastern end of King's Dock and Queen's Dock.

Several combined link and slide devices have been described, by means of which block diagrams can be constructed from contoured maps (1, 2). Briefly, their mode of use is as follows: (a) On tracing a contour with the tracing point of the mechanical device, the drawing pencil reproduces the contour as its isometric projection, i.e. distances along the supposed line of sight are reduced relative to distances measured at right-angles to this direction, the reduction factor being determined by the angle at which the area is assumed to be viewed. (b) Before drawing the isometric projection of the next lower contour, the sheet of paper on which the diagram is being made is moved relative to the map in a direction depend-ing on the type of device by a distance which depends on the scale of the map, the contour interval, the angle at which the area is viewed, and any factor of vertical scale magnification relative to the horizontal scale which is deemed necessary to bring out the topography (2). Each successive contour is treated in this manner, preferably starting with the highest contour and finishing with the lowest. In drawing the isometric projections of the contours, such parts are omitted as their inter-sections with the higher contour projections show to be obscured by the intervention of high topography between them and the point from which the area is viewed. (c) Finally hill sky-lines are filled in, roads, rivers, etc, are drawn by sketching between the points where they have been marked as crossing contours in dealing with each contour, and such artistic additions are made as will enhance the impression of relief.