a name applied in English indifferently to the Loligo vulgaris and the Sepia, animals belonging to the cephalopodous class of the Mollusca. The most remarkable characteristic of the tribe of animals to which the cuttle-fish belongs is the inky fluid which they emit when hard pressed by any of the numerous foes by which they are liable to be assailed. The organ in which this fluid is secreted is spongy and glandular. In some species it is contained in a recess of the liver, which has given rise to the opinion that the fluid in question was bile. In other species, however, this gland is detached from the liver and situated either before or behind that organ. The excretory canal of this gland opens in the rectum, so that the fluid escapes through the funnel. It mixes readily with water, and imparts to it its own peculiar colour. When dried it is used as a pigment, and is considered as the basis of china ink. It is obtained by digesting the ink with very dilute nitric acid, until it becomes yellowish, washing it well and separating it by the filter; it is then boiled frequently in water, one of the washings being slightly alkalized, and finally with distilled water. See Mollusca, class Cephalopoda.