Cydostome 



testis 



uroqenital 

 duct 



oviduct 



uterus 



male 



female 



kidney 

 bladder 

 ureter 



vgs deferens 



oviduct 

 ovary 



female 



Fig. 20-2. The urinary and reproductive systems were separated in lower vertebrates (cyclostomes) but became inti- 

 mately associated in higher vertebrates (fishes, amphibia, birds, and mammals). Three forms are shown here to 

 show how this came about. See the text for details. 



