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In addition to the eight Costodes noticed in my previous communication, all of which belong to the genus Tæria, we find the human host liable to entertain several Bethriocephali. These are readily distinguished from ordinary tapeworms, not only by the absence of true suckers on the head, but also by the circumstance that the reproductive openings are placed on the ventral aspect of the proglottides, and in the median line. The classification of the Cestodes, as a whole, requires revision, but no zoological arrangement will stand that is not based on the examination of a large number of types. In may be that the out-of-the-way types are difficult to get at and comparatively rare; nevertheless it is just these aberrant types that are wanting to the Cestode systematist. The hard and fast line drawn between the armed tapeworms and the unarmed forms cannot be allowed to remain, since rudimentary hooklets have been found attached to the margin of the supplementary suckerlet or central disk of the beef tapeworm. Of course, as a matter of mere convenience it is very useful to separate the hooked and hookless Tæniæ, but the separation is not fitting as a primary basis of classification. In like manner the snouted or proboscis-bearing tapeworms, (Rhyncholæliadæ,) considered as altogether distinct from the tapeworms that do not possess any proboscis or rostellum, (Arhyncholæliadæ,) cannot be accepted. Of far more significance and value is the proposal that we should divide the tapeworms into two sub-orders, based on the characters of the egg-shell. This originated with Dr. Weinland of Frankfort. Thus, for the thick or hard-shelled tapeworms, he proposed the term Seleroleptidota and for thin-shelled forms the term Malacolepiidota. The eggs of the former require the action of the gastric juice of vertebrates to dissolve their shells, whilst the eggs of the latter readily hatch within the stomach of evertebrated animals, such as mollusks and

insects. Quite recently, astonishment was expressed (in the pages of a scientific journal) that herbivorous animals (rabbits and hares) should suffer from the presence of tapeworm. It was evidently unknown to the writer that the larva of tapeworms (Cysticerei) are found in many other kinds of food than meat. To be sure, as Melnikow's discovery of the larvæ of Tænia rucumerina in the louse of the dog, (Trichoidœtes latus,) simply shows, "measles" are not necessarily swallowed as part of the ultimate host's food, but may be taken into the stomach accidentally. Respecting the question (raised by the President of the last meeting of the Section) as to the temperature necessary to destroy the eggs of tapeworms, I have no special information to offer, but

Erratum in April Number (p. 98, line 9).—For "muscles in the beast and in the connective tissues," read "muscles in the heart, and in the connective tissues.”