Manic types: Hypomania, Acute mania, Delusional and Delirious forms. Depressive types: Melancholia simplex, Melancholia gravis, Stupor, Paranoid, Phantastic and Delirious forms. Mixed types: Depressive mania. Excited depressions. Mania with poverty of thought. Manic stupor. Depression with flight of ideas. Retarded mania. The mixed and atypical forms are of special importance, as they occupy the middle ground between the classical types of manic-depressive insanity and dementia praecox. It is here that difficulties arise and errors in diagnosis are made. They have never received sufficient attention until recently. In practice many of these have undoubtedly been classed with the dementia praecox group. The first of these as described by Kraepelin is depressive or anxious mania—characterized by a depressive mood with anxiety and excitement and, at the same time, a flight of ideas. The patients are distractible, observant of everything in their surroundings, and complain that thoughts obtrude themselves upon them. Some have a mania for scribbling. Often there are delusions of persecution, sin, and hypochondriacal ideas. The mood is one of anxiety or despair. Impulsive acts are occasionally observed. They are inclined to weep, wring their hands, pull out their hair and throw themselves on the ground. Instead of a flight of ideas there may be poverty of thought and retardation with excitement—an "excited depression." The patients may be very wordy and monotonous in expression but are entirely clear as to their surroundings. The mood is anxious and tearful, often with delusions. There is a considerable excitement, but not of such a stormy character as in the depressive or anxious mania. Mania with poverty of thought, an "unproductive" form, shows a more cheerful mood but without a flight of ideas. This form Kraepelin speaks of as a common one. Speech is monotonous and expressionless. The patients present almost an appearance of feeblemindedness, although exceedingly variable and changeable. The mood is cheerful and sometimes irritable. The excitement is shown by jumping around, making faces, etc., but without any occupational activity. This alternates with periods of quiet when but little is said. They show no desire to occupy themselves in anything useful. Sudden outbursts of violence often occur. Stuporous, almost cataleptic forms with occasional delusions of a hypochondriacal type, fairly well oriented and with a clear sensorium, are spoken of as "manic stupor." This is interrupted by excitement and violence, with laughter, witty remarks and even eroticism. They often have a clear memory of all occurrences. This stuporous type may appear suddenly in an ordinary manic attack, or take place between excitements and depressions.