It is not our intention here to seek to provide a differential diagnosis between tic and the various conditions usually classed as myoclonus, and that for two reasons: in the first place, we cannot admit that the latter form a distinct clinical or nosographical entity, since the term myoclonus seems simply to be an abbreviation for clonic muscular convulsion, and is a symptom rather than a clinical syndrome; secondly, the fact that the tics themselves have been incorporated with myoclonus involves the investigation of all the published cases with a view to their critical sifting. This task we have pursued for our own edification, but to enter on it here would serve no useful purpose, and we shall rest content with examining succinctly several recent cases described as myoclonus, in the hope that the prosecution of further research will introduce order into what is at present chaos. * * * * * Among the various forms of myoclonus there is one which presents a certain individuality, and which was described originally by Friedreich under the name of paramyoclonus multiplex. This disturbance of motility supervenes, in patients with a neuropathic heredity, after some psychical accident such as a sudden fright or emotion, and consists in clonic muscular convulsions affecting the body generally, with the exception of the face. The contractions appear without obvious cause in one or in several muscles, are instantaneous, involuntary, and usually bilateral, but their most important feature is their inequality and irregularity. They may or may not effect displacement of the limbs; in any case they compose neither gesture nor gesticulation. Volition occasionally seems to have some transient inhibitory influence over them; they are exaggerated by cold and by emotion, and usually disappear in sleep. It is obvious that this account of a typical case precludes the possibility of any confusion with tic, but the published cases are not always in conformity with it. In 1892 Lemoine[181] reported a case where the movements of paramyoclonus multiplex were accompanied with echolalia and psychical changes. Raymond quotes an instance of the disease being preceded by facial tic, and another associated with tremor and choreic movements. D'Allocco[182] has recorded twenty-four cases of differing forms of myoclonus, of which nineteen occurred as a family disease, in conjunction with stigmata of degeneration, epilepsy, and hysteria. In a patient, aged twenty-six, suffering from general paralysis, Hermann[183] noted the presence of abrupt, irregular, myoclonic twitches in the sternomastoids, recti abdominis, adductors, and in some of the toes and fingers, first on one side and then on the other, also in both legs, and subsequently in both arms, the face being unaffected.