It is well known that the crushing teeth of the Pycnodont fishes as a rule are arranged with striking regularity upon the bones which bear them, the vomer in the upper jaw and the splenials in the lower jaw. They are disposed in longitudinal series, gradually increasing in size backwards, and there is only one genus satisfactorily known (Mesodon) in which there is any marked tendency towards the frequent disturbance of this linear arrangement.

The following notes have been drawn up from a study of specimens which were collected by G. F. Scott Elliot, Esq., during the earlier of two recent expeditions in Africa. He followed the Nile to somewhat beyond the second cataract, and brought back more than 130 examples of various rocks. The collection was sent to University College for examination, which I was allowed to undertake by the kindness of Professor Bonney, to whom I am further indebted for much help and advice on points of difficulty. A detailed description has been furnished to Mr. Scott Elliot to be included in the account of his journey, which it is to be hoped will be published before long. It may, however, be useful to have a short summary of the chief points of geological interest for general reference in an easily accessible publication.

Under the true Carboniferous strata of Ohio, that is below the base of the Berea Grit, lies a mass of shale of varying colour many hundred feet in thickness. The uppermost fifty or sixty feet are often red or reddish, and have been separated with the name of the Bedford Shale. The next layer, of about the same thickness, is usually black or at least very dark and bears the name of the Cleveland Shale. Below this again is a greenish mass 500 feet or more in thickness, known as the Erie Shale. Another dark bed follows—the Huron Shale—beneath which is the great limestone base of the Devonian in Ohio, the Corniferous.

Any geologist who, in these days, is still bold enough to affirm that the origin of Alpine Lakes generally is due to glacial erosion, must surely derive considerable comfort from a visit to the Upper Engadine; for the four lakes which adorn that valley appear, at first sight, to constitute so many typical examples of the erosive power of the ancient Inn glacier, and therefore a striking confirmation of that time-honoured theory. A closer and more extensive examination of the physiography of that exceedingly interesting district, leads, however, as in so many similar cases, to a very different, and precisely opposite conclusion.

Though the observations described in this note are not conclusive, they seem to me to show that the lake of Geneva is probably growing at the present time, and that a similar growth, if taking place beneath an ice-covering on nearly level ground, would in time produce a true rock-basin. Unfortunately, the instruments used were very delicate levels, and experiments with such instruments prove that they are not to be trusted entirely for measurements of very small angles continued over a long interval of time.

In addition to the localities in Europe and N. America, another area for Tertiary Mammals has in very recent times been laid open to view in the Southern part of Argentina, which promises in the wealth of its contents to exceed those previously known. A few scattered remains from the Tertiary beds of the neighbourhood of Santa Cruz in Patagonia were already known more than forty years ago, but it is only lately, through the work of Burmeister and Moreno, and more particularly through the indefatigable researches of Florentino Ameghino, that a more complete insight into this very remarkable fauna has been obtained.