Apart from its minuteness, moreover, this trematode is especially characterised by the possession of a very remarkable apparatus surrounding the reproductive orifices. It consists of an irregularly circular disk, measuring 1/125″ in diameter, and having a thick-lipped margin, which supports seventy fish-basket-like horny ribs comparable to the claw-formations seen in the genus _Octobothrium_. According to Bilharz these ribs give off five little branches from their sides, but Leuckart could not see them in his specimens. Leuckart estimated the length of these horny filaments to be 1/1250″, whilst their breadth was 1/3570″. On the whole we may regard this organ as a complicated form of “holdfast” designed to facilitate or give efficiency to the sexual act. I may here also state that this structure is by no means unique; for, if I mistake not, it exists in an equally developed degree in the young trematode which Dr Leared found infesting the heart of a turtle. Leared believed that he had found an ordinary distome; an opinion to which I could not give my assent, seeing that the organ described by him as a “folded, ventral sucker” presented a very different aspect to the oral sucker displayed by the same animal. Without doubt, however, the organ in his so-called _Distoma constrictum_ is analogous to the supplementary “holdfast” existing in _Distoma heterophyes_. The views which I originally advanced as to the source and condition of the parasite are probably correct. [Illustration: FIG. 4.--The small Egyptian fluke (_Distoma heterophyes_), viewed from behind. The large ventral sucker, supplementary disk, uterus, testes, simple divided intestine, vitellarium, and pulsatile vesicle are conspicuous. Original.] As regards the structure of _Distoma heterophyes_, I have only to add that a special set of glandular organs is situated on either side of the elongated œsophagus, but the connection between these organs and the digestive apparatus has not been clearly made out. Leuckart compares them to the so-called salivary glands found in _Distoma lanceolatum_, and says, “The presence of such a glandular apparatus is also indicated by the more ventral position of the oral sucker, and the development of the cephalic margin.” The conspicuous contractile vesicle terminating the excretory system is developed to an unusually large extent, exhibiting in its interior multitudes of the well-known active molecular particles. Lastly, I have only to add that the eggs of _Distoma heterophyes_ measure 1/990″ in length by 1/666″ transversely.