3165. Excretory system. 13 Color Photomicrographs. 1. Nephrostome of nephridium from earthworm 2. Kidney of snail, t.s. 3. Malpighian tubules of insect t.s. 4. Kidney of newt, primordial kidney, t.s. 5. Nephrostome with ciliated funnel in kidney of frog 6