Smithsonian Report. 1936.— Pycraft 



Plate 5 



1. Stages in the degeneration of the pelvic limb from functional organs to vestiges, in different individuals, 



Balaenoptera physalus. 



2. Stages in the degeneration of the pelvis in different generations of the Sirenia from Eocene times to the 



present day. 



Vanishing Organs. 



