John Overend was attacked with pain in the right thigh and loins, which were considered as rheumatic. Shortly after the thigh was observed to be elongated, and issues were applied over the hip joint, upon the supposition of its being a common case of morbus coxarius. But no considerable relief was obtained by this; on the contrary, the upper part of the thigh swelled, whilst the lower part wasted, his appetite diminished, his pulse was quickened, and he passed sleepless nights. The thigh was rubbed with anodyne balsam, and draughts with laudanum were given every night, but only with temporary benefit. For the course of some months these complaints continued, with occasional remission and aggravation. At last he began to complain of difficulty in making water; and this soon ended in a complete retention. The catheter was attempted to be passed; but although its point was bent, and directed so as to correspond to any deviation of the prostate gland from its right situation, it could not be introduced. By examining per anum, a large elastic tumor could be felt in the pelvis, which was considered as the bladder. A trocar was therefore passed up the rectum, and the bladder attempted to be tapped. A considerable quantity of bloody fluid came away; but he complained of no pain at the glans, which most patients do when the bladder is wounded; and a considerable quantity of high coloured fœtid urine was voided by the urethra, and continued even afterwards to be passed, although with some difficulty. Within a week after this the patient died. On dissection, I found the hip joint to be completely surrounded with a soft matter, resembling the brain, inclosed in thin cells, and here and there cells full of thin bloody water; the head of the femoral bone was quite carious, as was also the acetabulum. The muscles were quite pale, and almost like boiled liver, having lost completely their fibrous appearance, and muscular properties. On opening the abdominal cavity, the same kind of substance was found within the pelvis; and the greatest part of the inside of the bones of the affected side were quite carious. Large cells were found in this diseased substance, containing bloody water; and it was into one of these that the trocar had entered when the bladder was attempted to be tapped. CASE III.