Science. 1964 May 29;144(3622):1151-2. doi: 10.1126/science.144.3622.1151.
The rectal glands of elasmobranchs perform the function of salt-excreting organs. These glands are smaller and show regressive changes in specimens of the bull shark, Carcharhinus leucas found in fresh-water environment, compared with specimens of this and other species from a marine habitat.
软骨鱼类的直肠腺具有排泄盐分的功能。在淡水中发现的牛鲨（Carcharhinus leucas）标本中，这些腺体比来自海洋生境的同种和其他种鲨鱼的标本更小，并且发生了退化变化。
