long diameter of about 1/200″, by 1/330″ in breadth. They are therefore somewhat smaller than those of the common fluke. In the specimen preserved in the Hunterian Museum there was complete evidence of the presence of an excretory outlet at the caudal extremity; but I did not succeed in finding any trace of the water-vascular system higher up. I have no doubt, however, that it exists. As regards the affinities of _Distoma crassum_, it is clear that this Trematode has little in common either with the liver-fluke of cattle and sheep (_Fasciola hepatica_), or the still larger species obtained by me from the giraffe (_Fasciola gigantea_). The simple character of the digestive tubes obviously connects it more closely with the lancet-shaped fluke (_Distoma lanceolatum_), the last-named parasite being, as already shown, an occasional resident in the human liver, where its presence, moreover, undoubtedly contributed towards the production of the fatal result. In my remarks on the missionary’s diet it is hinted that the Ningpo oysters may have played the _rôle_ of intermediary bearers to the parasite in question; and as tending in some measure to strengthen this notion, it should be borne in mind that Mr. Busk’s original fluke-bearer came from the east. It is not improbable that the Lascar host may have partaken of the same particular species of fish or shell-fish that the missionary and his wife partook of. Be that as it may, the frequency of the occurrence of Trematodes and their larvæ in marine mollusks is well known. According to Woodward, several species of oyster are sold in the Indian and Chinese markets. Thus, it would require the skill of a malacologist to determine the particular species of _Ostrea_ to which the Ningpo oysters should be referred.