My examinations of the ova and embryos were chiefly made from the “sediment” sent in a special glass tube. The fully formed embryos were 1/125″ in length by 1/2500″ in breadth. They each showed a double skin, the outer envelope in the more advanced specimens leaving clear spaces at either end of the body, resulting from commencing ecdysis. I saw no trace of intestinal tube, but a central line of condensation marked an early differentiation of the somatic granular contents. The less advanced embryos were mostly enclosed in a chorional envelope, the smallest free embryos measuring only 1/200″ in length by 1/3000″ in breadth. These had no double contour. The ova, whose yolk-contents were still in various stages of cleavage, gave an average long diameter of 1/900 to 1/1000 of an inch. Such are the facts I made out, and they enabled me to amend the characters of the species. As regards nomenclature, I associated Dr Bancroft’s name with the sexually-mature worm as being in harmony with the binomial method and little calculated to mislead; moreover, it helped to fix both the source and date of the discovery (Brisbane, Dec. 21st, 1876). The use of this nomenclature detracts nothing from the high merits of Lewis, who first named the immature worm _Filaria sanguinis hominis_. As it now turns out, both Dr Salisbury and myself had previously been made acquainted with the young of _Filaria Bancrofti_; but it was reserved for Lewis to discover the hæmatozoal character of the embryos of this worm, and actually to take them from the blood. It was a singular circumstance, that when I was engaged in treating my little African patient for trematode hæmatozoa, it never once occurred to me that the numerous nematoid embryos mixed with the Bilharzia ova were hæmatozoal. As before remarked, it was alleged that my patient had passed worms two or three inches long by the urethra. I therefore concluded that these were the parents of the eggs and embryos, and that all of them were urinary. The inference was wrong, but it has instructively shown how near one may go towards a great discovery without really making it. As regards the larvæ, notwithstanding some slight differences in regard to size and so forth, I have little hesitation in saying that all the embryo forms severally described by Salisbury, by myself, by Lewis, Sonsino, Wucherer, Crévaux and Corre, Silva Lima, Bancroft, Manson, and others, are referable to one and the same species.