In a communication to the International Medical Congress recently reported in some of the English newspapers, Professor Arthur Keith expressed complete disapproval of my reconstruction of the skull and mandible of Eoanthropus Dawsoni. I concluded that the brain capacity of this skull was comparable only with that of some of the lowest existing savages, while the mandible must have been provided in front with teeth of the ape pattern. Professor Keith, on the other hand, has restored the skull in such a manner as to have a brain capacity of 1,500 cubic centimetres, thus exceeding that of the average modern European. By distorting the curve of the front of the mandible he has also furnished it with completely human teeth. These two views, therefore, need careful examination before any definite conclusions can be drawn from this remarkable fossil.

I am content to leave to the readers of the Geological Magazine the question whether Colonel Burrard's theory of the elevation of mountains and Mr. Hayford's of the distribution of density to cause isostasy are more in accordance with geological phenomena than my theory of mountain roots supported in a dense liquid substratum. But in Colonel Burrard's reply to my paper in the Magazine for June there is a fundamental but specious error. I wrote: “Is it not possible that the earth's rotation may impart to it a ‘gyroscopic’ quasi rigidity, which may enable it to withstand the deforming influence of external forces [the attraction of the moon and sun], although at the same time forces internal to the earth will be unaffected by it.” To this Colonel Burrard replies: ”Mr. Fisher has argued that the rotation of the earth will give to the liquid interior an effective rigidity; but this rotation has conferred no rigidity upon our oceans, and even if it did render the liquid interior rigid, it would only do so in low latitudes where the rotation velocity is high. I understand, moreover, that the earth's interior was assumed by Mr. Fisher to be liquid, in order to explain the floatation of the crust. If the liquid is now proved to be rigid, the crust cannot be floating upon it.”

The original figure of this species was rather diagrammatic and requires supplementing. Figs. 1 and 2 are from the type-specimen, Fig. 2 being given to illustrate the rectangular aperture which the species has a tendency to develop, though quite irregularly; this rectangular outline appears to be due to the amalgamation of the two prominent tubercles into a straight-edged cap which hides the arched part of the upper lip and may be oœcial in function. The typical form of the species is definitely established in the Marsupites zone (= Marsupites band of many authors), though it only becomes abundant in the succeeding zone.

I Do not think there is likely to be much gain from a prolonged discussion of this matter, and for the present I shall content myself with a brief recapitulation of the position so far as it affects the views of Dr. P. Marshall on the one hand and of Captain Hutton and myself on the other.

More than twenty years ago, whilst engaged in the study of the Lower Carboniferous rocks of Westmorland, I noticed the occurrence of certain small concretionary nodules of very compact texture in the dolomites near the base of the succession in the neighbourhood of Shap.

Probably most teachers of petrology have experienced difficulty in making clear to some elementary students the manner in which light is transmitted through a polarizing microscope, and the explanation of birefringence and pleochroism. In such circumstances I have found very helpful the analogies illustrated by an easily constructed model. Doubtless such an instrument has been used before, but, as the textbooks make no mention of it, a description may be of use here.