Pint (Ontario), about 1 litre versus 0.5 litres. After four of the British provinces united in the Canadian Confederation in 1867, Canada legally adopted the British imperial system of measure in 1873, making Canadian liquid units incompatible with American ones from that year forward. In 1873, the French Canadian "pinte" was defined as being one imperial quart or two imperial pints, while the imperial pint was legally called a "chopine" in French Canada. Canadian imperial units of liquid measure remain incompatible with American traditional units to this day, and although the Canadian pint, quart, and gallon are still legal units of
External gills salamander species, such as most members of the Proteidae family (the olm and mudpuppies) and the Sirenidae family, which naturally never metamorphose into an air-breathing form. The embryos of frogs and caecilians also develop external gills at some point in their development, though these are either resorbed before or disappear shortly after hatching. Fossils of the distant relatives of modern amphibians, such as "Branchiosaurus" and "Apateon", also show evidence of external gills. The external gills commonly consist of a single stalk (rami) protruding from a gill arch behind the head of the animal, above an associated gill slit. The stalk