DICHOTOMY. 129 
represented in fig. 73, a third hind limb projecting 
posteriorly between the normal legs. On dissection it 
was found attached by muscle and tendon to the 
symphysis pubis: it presented the usual segments of 
femur, crus, and pes, and was furnished with two 
well-formed digits and the rudiment of a third. 
During life it was found that when the skin of the 
limb was stimulated the frog would jump quickly 
away ; sometimes oft-repeated stimulation would call 
forth a muscular contraction 
in the limb. Occasionally 
movements were observed 
in the abnormal limb when 
the frog was left entirely to 
itself. 
It has already been men- 
tioned that in parasitic 
foetuses, even when the ; 
limbs are well-formed, the Jagr 
autosite has rarely the power 
Fic. 73.—A Frog (Ranaj palustris), 
with supernumerary hind limb, 
the limbs belonging to the (After Tuckerman). 
parasite, and this is the rule in supernumerary limbs, so 
that the spontaneous movement in the leg of Tucker- 
man’s frog is interesting, The drake (fig. 74) pos- 
sessed the power of moving the abnormal limbs, and 
of spontaneously moving 
similar specimens have come under my notice in hens. 
Such power is, however, exceptional. 
Supernumerary pelvic limbs similar to those of 
frogs and toads, sheep and birds, occur in the human 
subject ; several of the individuals thus affected have 
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