A non-purulent inflammation of the meninges was already recognized forty years ago, when Quincke [1] first described a number of cases which he called " meningitis serosa." His group was widespread and associated with all manner of toxic illness, including typhoid, pneumonia, nephritis and disorders of pregnancy. Even continual mental strain and over-indulgence in alcohol were thought to be possible causes. In the present-day medical literature Quincke's conception has been somewhat mbdified. The type of serous meningitis which figures most consistently is that associated with suppuration in the middle ear and mastoid region, whilst that met with in pneumonia ie generally referred to as meningism. The particular serous meningitis I wish to discuss to-day is somewhat different. Abroad during the last few years it has from time to time assumed epidemic proportions, and has therefore naturally received more attention than in this country, where only a few sporadic cases have been published by Gibbens [2], Gordon and Abrahams [31, Rankin [41, and a questionable epidemic of the same condition by Braithwaite and Innes [561 Personally, I can only add two more such cases which