In the summer of 1908 one of us (E. N. P.), whilst collecting material in the River Zeravshan in the vicinity of Samarkand (Turkestan), came across a case of adhesive peritonitis in a local fish, Schizothorax intermedius. The abdominal wall of this fish, with a part of the viscera adhering to it, were dissected out and placed in 70 per cent, alcohol where they remained untouched till 1919 when we proceeded to their examination. The results of our investigation are described in this paper. An examination of the excised parts shows a compact accumulation of tissue on the ventral side of the intestinal coils, in the form of a flat patch from which a series of fine strands run to the black peritoneal covering of the lower body-wall. The patch which shows irregular edges is coloured black and is covered with yellowish spots.