Although the term "sinistrality" usually suggests merely the idea of left-handedness, it is collective in its significance and embraces various manifestations obviously due to functional predominance on the part of the right cerebral hemisphere. Here it is used, in a somewhat restricted sense, in connection with certain paired activities of the upper extremities and the eyes, sometimes spoken of as handedness and eyedness. Remarkable though they are, these coordinated activities of the hands and eyes seem to have attracted comparatively little attention. Clinically, they are easy to recognize. There are four principal forms, two of them being symmetric and two asymmetric. The two symmetric or homonymous forms are best known. They were defined first, I believe, nearly fifty years ago, by Prof. Joseph Le Conte.1 Since his description of these peculiarities will serve well for the present purpose, I shall quote his words. Under the caption "Double Images," he