i 2 6 EVOLUTION AND DISEASE. 



clear that if dichotomy lead to reduplication of the 

 pelvis, four pelvic limbs should result In typical 

 specimens such is the case : two of the limbs being 

 functional, and two usually occupying a median position 

 on the ventral aspect, much smaller in size. 



FlG. 70. Rana esczilenta, with supernumerary hind limbs. 



A specimen of this nature was described in 1837 by 

 Dr. J. van Been. It occurred in a frog (Rana esculentd], 

 (fig. 70), and was associated with a bifurcated condition 

 of the termination of the alimentary canal. Van Been 

 gives a carefully detailed account of the dissection of 

 this frog. It seems to be one of the earliest recorded 



