Bothriocephalus latus, a parasitic worm belonging to the class Cestoda. It is nearly allied to Taenia, solium, the common tapeworm, but attains a larger size than that parasite ever does, some specimens being as much as 25 feet in length. The adult form occurs in man, in dogs, and in cats; it is, however, only met with in certain parts of Europe, particularly in Russia and Sweden. Dr. Braem, of Dorpat, has shown that the embryo or cysticercus form inhabits the muscles and viscera of certain pikes and eels; and if such infected fish be eaten by man in a half-cooked condition, the parasite obtains access to the human intestinal canal, where it undergoes its remarkable development. The embryo attaches itself by its hooklets to the wall of the intestine, and rapidly increases in length by the growth of a series of segments. The adult worm has no hooklets, but is provided with two suckers; the segments are as a rule broader than they are long, and the genital sore is situated in the middle of the flat surface, and not laterally as in the common tapeworm.