Urinogenital Organs of a Vertebrate
Diagrams illustrating the development of the urinogenital organs of a vertebrate. A, pronephros and segmental duct; B, atrophy of pronephros, development of mesonephros; C, appearance of Mullerian duct; D, development of metanephros, male type; E, the same, female type. The sex gland, ovary and testis is obliquely shaded; phonephros and mesonephros unshaded, metanephros stippled; Mullerian duct heavily shaded. The large chamber to the right, into which these ducts as well as the intestine open, is the cloaca.
Beach, Fredrick Converse The Encyclopedia Americana (New York, NY: The Americana Company, 1903)