“…Gordon, Schmidt-Nielsen & Kelly (1961) showed this, using frogs collected from brackish water; and Colley, Rowe, Huggins, Elliott & Dicker (1972) showed it in frogs collected from fresh water. It has been pointed out by Dicker & Elliott (1973) that whether the frogs are collected from fresh water or from brackish water, the plasma urea level is always higher than in other anuran amphibians; and Chew & Elliott (1971), and Chew, Elliott & Wong (1972) have discussed the function of urea when the rain or tide changes the salinity of the environment of the frog. It is clear therefore that an adequate intake of nitrogenous food will be necessary for R. cancrivora, so that it may have the necessary urea for osmoregulation.…”