XIV, 2 Carreon: Absence of Both Hind Legs in a Pig 203 
In as much as all of the other pigs in the litter were nor- 
mally developed, we can at once exclude the probability that 
uterine inflammation may have interfered with the normal pro- 
cess of development. It seems probable on the other hand that 
a faulty implantation might produce a pathological condition 
such as we found in this specimen. The cause in this case may 
have been primarily a mechanical one that was reflected on the 
embryo, thus producing the malformation. The presence of 
the appendages attached to the skin overlying the distal end 
of the femur seems to indicate that the extremities were more 
developed at some previous time. However, when the factor 
that produced the malformation appeared, the further develop- 
ment of the palate and the hind legs ceased. 
In making this report I am indebted to Prof. Edward S. 
Ruth and the members of the anatomical staff for valuable cri- 
ticisms and suggestions; for all of which I wish to express my 
appreciation. 
