These are characterized by their enduring growth, and by the great length to which they attain. They consist of a succession of linked joints, of which the fully developed, sexually mature, hindmost ones become cast off in greater or lesser series; whilst at the neck, fresh joints are continually being reproduced. As in these, again, a brood is rarely seen associated with the old individuals, whilst the separated, sexually mature joints so frequently become ejected, it is probable that the em-bryones become developed externally to the animal they infest, to re-immigrate subsequently.

In mankind there occur:

The Toenia solium, T. vulgaris, T. cucurbitina, the ordinary tapeworm, long-jointed tape-worm, chain-worm; a white, or yellowish-white worm, twenty feet long and beyond it, anteriorly thin, roundish, - posteriorly flat, and from three to six lines broad, - jointed. The joints are flat, square, towards the distal end more and more oblong-square, resembling gourd-seeds with truncated apices. At the right or left margin, often alternately, is seen a wartlike projection marked by a pore with a raised brink. This is the orifice of the sexual organ, which represents a cavity dendritically branched throughout the joint. The head constitutes at the very thin anterior termination, a nodule-like intumescence, with four lateral, black points in relief. There are four suction pores; and, between them is seated upon a slightly raised circle a double coronet of booklets. The annulate neck is studded with numerous lime-corpuscles of the most various size (vide Cystica).

Inhabits the small intestine in man, almost in all districts, except where the botryo-cephalus occurs. The belief that it only occurs singly in man is quite adverse to experience. We have discovered nine of them in the corpse of a lad. It occasions the well-known annoyances, but no visible anatomical mischief.

Botryo-cephalus latus, taenia lata, the broad or broad-jointed tapeworm, resembles the last in many points, equalling it in length, and being in like manner jointed. Its joints are usually broader than those of the T. solium; this alone, however, cannot pass for a diagnostic mark. The wartlike projections are not, as in the other worm, seated at the margin, but at the centre of the ventral surface. Their pore leads to a branched rosette-shaped, sexual organ. The head, differing from that of the T. solium, exhibits no suction-pores, but two longish grooves.

Inhabits the small intestine in man, but is strictly limited to Russia, Poland, Prussia [trans Vistulam], Switzerland, and to the South of France. If it occur elsewhere it is assuredly imported from one of those countries.

It rarely parts with single joints or links, but usually with a greater or lesser chain of them.