Internal Anatomy of the Grass Frog [Genus Litoria]
As different as frogs are from you and I, you can clearly see how similar vertebrates are to each other when you dissect one. One heart, two lungs, a stomach, liver, spleen, gall bladder, intestines, kidneys, bladder, and gonads are visible in this particular dissection, as well as the extraordinarily strong leg muscles.
Brehms Tierleben, Bd. 1. Alfred Brehms, 1911.