The communication received from Dr Dyce chiefly consists of a description of a singular affection of the nervous system, and mental powers, to which a girl of sixteen was subject immediately before puberty, and which disappeared when that state was fully established. It exemplifies the powerful influence of the state of the uterus on the mental faculties; but its chief value arises from some curious relations which it presents to the phenomena of mind, and which claim the attention of the practical metaphysician. The mental symptoms of this affection are among the number of those which are considered as uncommonly difficult of explanation. It is a case of mental disease, attended with some advantageous manifestations of the intellectual powers; and these manifestations disappearing in the same individual in the healthy state.