distoma

[Gr.di= dis =twice, twofold, and stoma=a mouth.] Zoology: 1. A genus of internal parasitic worms, order Trematoda, cla Plat yelm i nth a, vulgarly known as "Suctorial Worms" or "Flukes." The Distoma is commonly found in the liver and biliary ducts of sheep and other ruminants, deriving nourishment from the fluids in which it is immersed, and giving rise to the disease known as the "rot." The body of the creature, which is not quite an inch in length, is flattened, and resembles in some degree a minute sole or flat-fish: at its anterior extremity is a circular disc, or sucker, which is perforated by the aperture of the mouth; while a second sucker of similar form, but imperforate, is placed upon the ventral surface of the body. With these, both formerly thought to be mouths, whence the name, the parasite clings firmly to the body of its host. The embryo on its discharge from the egg is of conical form and aquatic habits, swimming freely by means of cilia, with which it is covered. These, however, it does not retain long, and pa ing into its second stage of development. it enters the body of some fresh-water mollusk, where it remains until its temporary host is accidentally taken into the system of some ruminant, when it undergoes its final transformation and pa es into its mature stage of development. Distoma has occasionally been found in man. 2. A genus of Mollusca, order Tunic at a, family Botryllidae. They occur on marine Alge. Branchial and anal orifices six-rayed.