From the size and almost leathery texture of the two flukes which were in the first instance submitted to my notice, I at once recognised the species; but as they were spirit-specimens, I requested that if any more examples were obtained they should be sent to me in the fresh state. Fortunately others were brought in a few days, when, from an examination conducted whilst they were still fresh, I was able to make out several details of structure which had hitherto escaped notice. Altogether I secured seven specimens, three of them being in a mutilated condition. In what way these mutilations (as shown by my dried specimens) occurred I have not been able to make out, either by personal observation or by questioning the bearers. Two of the parasites look as though portions had been carefully excised near the centre. The new facts I have gleaned were derived from the examination of two comparatively small specimens, one of which, dried, has, by Prof. Rolleston’s desire, been deposited in the anatomical department of the University Museum at Oxford. When I took occasion to bring some of the new specimens under Mr Busk’s attention, he at once recognised them as referable to the species he had long ago discovered. The earliest literary notice of _Distoma crassum_ appeared in Dr Budd’s classical treatise ‘On Diseases of the Liver;’ and in it the author correctly stated, from data supplied by Mr Busk, that these human flukes were “much thicker and larger than those of the sheep,” being, it is added, from “an inch and a half to near three inches in length.” The longest of my recent specimens, however, scarcely exceeds two inches, whilst the smallest and most perfect (the one at Oxford) measures less than an inch from head to tail. The greatest width of my broadest specimen is little more than half an inch, or 9/16″. None of the twelve examples that I have examined approach the length of three inches; but Mr Busk assured me that, judging from his recollection, some of his specimens were even longer than that. I fear, nevertheless, that the estimate given in my Synopsis is somewhat exaggerated; at all events it is so for average specimens. [Illustration: FIG. 2.--The large human fluke (_Distoma crassum_) _a_, Oral sucker; _b_, intestine; _c_, cæcal end of same; _d_, reproductive papilla; _e_, uterine rosette (the folds of which are not branched); _f_, one of the folds (in profile); _g_, vitellarium; _h_, hernial protrusion (the result of an injury to the specimen); _i_, upper testis; _j_, streaks or layers of seminal fluid which have escaped by rupture and assumed a branched appearance; _k_, lower testis uninjured (but slightly altered in outline from flattening); _l_, ventral sucker. Magnified 2 diameters. Original.]