176 Dr. T. A. Chapman on some Teratological Specimens. 
and appendages. I have here placed a normal limb, as 
with the C. nupta, for comparison. The affected joints are 
apparently fractionally shorter than normal, but perhaps a 
little wider than the healthy one. The basal joint of 
course is much broader, and may be regarded as _ three 
joints fused side by side. 
My experiments in regenerations of limbs, of which I 
have not yet published a large number, performed some 
years ago, lead me to believe that these supernumerary 
limbs are all instances of regeneration, or if not all, at 
least a large proportion of them ; just as lizards occasion- 
ally regenerate two or even three tails. 
I picture the group of embryonic cells, which form the 
regenerative centre, broken up, by the injury by which 
the limb is lost, into two or more portions ; and each of 
these portions performs its functions of developing into a 
new limb without reference to the others. This result, is 
sufficiently rare to make it probable that injury rarely 
divides up this no doubt very minute portion of tissue, and 
that when it does, the divided portions succeed in most 
cases in reuniting, or all but one of the separated portions 
are mortally injured. 
All three specimens have been placed in the Natural 
History Museum, South Kensington. 
EXPLANATION OF PLATE XII. 
[See Explanation facing the PLate.] 
