Estratto dall’ Imparziale,’ Firenze, 1876.--_Idem_, ‘Sugli ematozoi come contributo alla Fauna Entozooca Egiziana,’ Cairo, 1877.--_Idem_, “La Bilharzia hæmatobia, et son rôle Pathologique en Egypte,” ‘Arch. Gén. de Médicine,’ for June, p. 650, 1876.--_Idem_, “Intorno ad un nuovo Parassita del bue (_Bilharzia bovis_),” ‘Estr. dal Rend. del. R. Accad. di Napoli,’ 1876.--_Weinland, D. F._, l. c., p. 67, 1858. SECTION II.--CESTODA (Tapeworms). _Tænia mediocanellata_, Küchenmeister.--This cestode is frequently spoken of as the unarmed or beef tapeworm. In general appearance it is very similar to the armed form. It is, however, a larger and broader animal, being at the same time rather stouter. It varies usually from fifteen to twenty-three feet in length, but specimens have been described as attaining thirty feet. It is called the unarmed tapeworm in consequence of the absence of any coronet of hooks on the head; and consequently, also, from there being no prominent rostellum or proboscis. The place of the last-named structure, however, is supplied by a small rudimentary disk, which I have seen protruded on pressure (fig. 20). Usually this disk forms a more or less conspicuous cup-shaped circular depression, which has been compared to and described as a fifth sucker. That it is not, in any structural sense, comparable to the true suckers, I have had abundant opportunity of ascertaining; nevertheless, I do not doubt that it is to a slight extent capable of being used by the parasite as a supernumerary holdfast. The anchorage thus secured, however, is by no means equal to that obtained by the armed species. This explains the comparative difficulty we find in procuring a specimen of the armed tapeworm with the head attached. [Illustration: FIG. 20.--Head of _Tænia mediocanellata_. Showing the calcareous corpuscles, suckers, rudimentary proboscis, and water vessels. Highly magnified. Original.] The establishment of this species as distinct from _T. solium_ is due to Küchenmeister; but it is curious to observe how accurately this determination was foreshadowed by the shrewd naturalist and theologian, J. A. E. Goeze, who clearly indicated two forms of the common tapeworm, remarking (l. c., Bibl. No. 1, s. 278):--“Die erste ist die bekannte grosse, mit langen dicken und gemästeten Gliedern, die ich _Tænia cucurbitina, grandis, saginata_, nennen will.” The same author (s. 245) pointed out the resemblance subsisting between the tapeworm of the cat (_T. crassicollis_) and the vesicles (“Krystallblasen”) and their contained “erbsförmige Blasen” (_Cysticercus fasciolaris_) of the mouse. Thus the celebrated pastor of St Blasius, in Quedlinberg, almost contemporaneously with Pallas, early arrived at the conclusion that the hydatid-measle was a kind of tapeworm. [Illustration: FIG. 21.--Free proglottides of _Tænia mediocanellata_. After Leuckart.]