External gills usually contains muscle tissue, and may be moved by the animal as a free appendage, in order to stir up stagnant water. The stalk is lined by many thinly walled filaments (fimbriae), containing the majority of blood vessels used in gas exchange. Animals usually have one external gill originating on each gill arch (except the hyoid), which leads to there being three pairs of external gills in salamanders, and four in the gilled larvae of lungfish. External gills External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside
Pint or "octarii"; symbol O) reflected the "eighth" concept in its "octa-" syllable. Because of the variety of definitions of a gallon, there have been equally many versions of the pint. America adopted the British wine gallon, defined in 1707 as 231 cubic inches exactly (3 in × 7 in × 11 in) as its basic liquid measure, from which the US wet pint is derived; and the British corn gallon ( of a standard "Winchester" bushel of corn, or 268.8 cubic inches) as its dry measure, from which the US dry pint is derived. In 1824, the British parliament replaced