I THINK that Prof. Macalister and his colleagues have quite fairly stated their opinion (NATURE, Dec. 31, 1927) upon the geological aspect of the sites examined by Mr. Burchell in Sligo. So far as I am concerned, I do not feel entitled to discuss or argue upon the details of this aspect of the matter, for the reason that as I made clear in my original note in NATURE—I have not yet visited the sites in dispute. I have, however, had abundant opportunities for making an examination of the specimens collected by Mr. Burchell, and of subjecting them to a prolonged and careful examination; and I entertain no doubt whatever that these specimens are humanly flaked, and that their forms and method of flaking are such as were in vogue in Early Mousterian—palaeolithic times. Further, I am of opinion that no natural force—or combination of natural forces capable of flaking stone—such as fortuitous pressure, percussion, or thermal action, could in any circumstances produce these forms. This is my sincere belief, and it is because I possess it that I consider it my duty to support Mr. Burchell in this matter.