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I feel sure I need not apologise for bringing under the notice of workers in Science a list of the human Entozoa and Ectozoa. No complete and trustworthy record, brought down to the present time, exists. In view of rendering my list less bald than a mere catalogue of species would inevitably prove, I shall append a few particulars relating to the synonymy of each parasite, its larval condition, and the organ or tissue of the hast it usually occupies. Omitting the Protozoa, I confine my attention to the following six parasitic groups:—1. Trematoda; Flukes. 2. Cestoda; Tapeworms. 3. Nematoda; Roundworms and Threadworms. 4. Acanthocephala; Thorn-healed worms, 5. Insecta; including all such dipterous, aphanipterous, and hemipterous insects as are either wholly or partially parasitic. 6. Arachnida: including all those trachearian forms, such as the mites and their allies, which are often vulgarly and erroneously termed scab, or itch-insects. Such is the bill of fare that I have now to offer, and, should it be found presentable and useful, it is proposed to follow it up at some future time by the publication of similar lists relating to the parasites of the horse and other domesticated animals.

As I cannot have the pleasure of reading these papers personally to the Section, and as I am desirous of making them as generally interesting to the members as the subject will permit, I have requested my friend, Mr. W. B. Hughes, to communicate the papers, and to exhibit some specimens on my behalf. The slides and preparations from my cabinet will be chiefly illustrative of the more remarkable forms of Entozoa enumerated in the lists.

1.—Fasciola hepatica, Linnæus. Synonymy.—Distoma hepaticum, Reizius and Ramdohr; Planaria, Gooze.

Larval state—An armed Cercaria; not yet distinguished. Free ciliated embryo conical.

Intermediate Host.—Not known. Probably a fresh water snail.

Remarks.—The common liver fluke of Ruminants has been found at least fifteen times in the human body.

Literature— All standard works on Helminthology (Leuckart, Davaine, Kitchenmeister, Dujardin, Cobbold.)

2—Distoma lanceolatum, Mehlis.

Syn.—D. hepaticum. Zeder and Rudolphi; Dicrocælium, Dujardin and Weinland; Fasciola, Bloch, Planaria, Goeze,

Larvæ.—Carcaria, form unknown. Free ciliated embryo globular.

Int. Host, —Not known. Probably a fresh water snail.