The museum at Oxford contains some choice specimens of hydatids, but I have only personally inspected a few of them. In the absence of original notes, however, I am indebted to the kindness of Mr W. Hatchett Jackson for supplying me with several interesting particulars. The anatomical department of the Oxford Collection shows from one particular case two hydatids that were found “under the dura mater.” In the pathological department we find one hydatid from the liver of a male subject, and also a preparation showing a number of small hydatids that were “coughed up from the lungs of a female.” There are also in this department (Dr. Acland’s) two examples of hydatids from the diaphragm, apparently belonging to two separate cases. One is described as a large “hydatid in the diaphragm covered by the pleura,” whilst the other is spoken of as “springing from the diaphragm and projecting into the sac of the pericardium.” There is likewise a preparation showing a number of small specimens of hydatids that were passed _per anum_ by a female. It is conjectured that they came from the liver. The small pathological museum attached to the Brighton and Sussex Hospital is particularly rich in hydatids. Amongst others, it contains preparations illustrative of the remarkable case of hydatids in the region of the prostate, communicated by Mr Lowdell, in the ‘Lancet,’ in 1846. The comparatively large museum adjoining the Norfolk and Norwich Hospital displays a choice series of hydatids, chiefly from the collection of the late Mr Crosse. That eminent surgeon prepared a special set of specimens to illustrate the process of natural cure by calcareous degeneration; and I may here, perhaps, be pardoned for mentioning that it was the study of these and other entozoa in Mr Crosse’s Collection, some thirty or more years ago, that first drew my attention to the phenomena of parasitic life. Illustrations of the helminths in question are still in my possession. In one case (which is instructive as indicating the possibility of death from the simplest form and commonest habitat of an hydatid) a lad, twelve years old, received a slight blow from a playmate. Something gave way, and death speedily followed. It was found by post-mortem examination that a solitary liver hydatid, rather larger than a cricket-ball, had been ruptured. Although the case is almost unique, it is nevertheless by no means pleasant to reflect upon the fact that under similar circumstances a slight blow might prove fatal to any one, no matter in what internal organ the bladder worm happened to be situated.