The museum connected with St Mary’s Hospital Medical School, in addition to several liver cases, contains one interesting example of hydatids of the lung (Dr Chambers’s case), and also three valuable preparations illustrating Mr Coulson’s remarkable case of hydatids affecting the tibia. One of the preparations shows the bone itself, which was eventually removed at the joint, the operation having been performed by Mr Spencer Wells. Here, perhaps, it will not be out of place to mention as a fact of special clinical interest that I have encountered records of no fewer than nine other similar cases where hydatids have taken up their abode in the tibia, generally selecting the head or upper part of the bone. Some of my notes have been mislaid, but, speaking from recollection, one of the choicest specimens which I have examined is that contained in the pathological museum of the Nottingham Hospital. When I first went over the collection of the Middlesex Hospital Museum, I found it to contain fifty-four preparations of entozoa, of which some fourteen only were true hydatids, representing as many separate cases. There are now upwards of a score of preparations of hydatids, several of the cases having already had ample justice done to them by Dr Murchison in his well-known memoir (‘Edinb. Med. Journ.,’ Dec., 1865). Amongst the most interesting preparations I would especially call attention to two fine and genuine specimens from the kidney, another very large example of an hydatid situated between the bladder and rectum, a simple acephalocyst removed from the orbit (Mr Hulke’s case), and the hydatid removed from the axilla by the late Mr Charles Moore. There is a jar containing hundreds of hydatids that were taken from the thoracic cavity of a dissecting-room subject, who was reported to have died of phthisis; and there is another preparation of an hydatid of the heart, which also proved fatal, without there having been the slightest suspicion entertained as to the true nature of the disease. For this fine preparation the museum stands indebted to Dr Moxon, of Guy’s Hospital. Several of the liver cases are particularly instructive; but amongst the specimens presented by Mr Mitchell Henry is a small bottle full of minute hydatid vesicles, all of which were removed from the interior of the tibia. The history of this case has been lost; and, unfortunately, the bone from which the parasites were taken does not appear to have been preserved.