DICHOTOMY, 127 



cases of this malformation. A much commoner con- 

 dition is to find the abnormal limb projecting posteriorly 

 between the normal legs. In such a position the two 

 legs are as a rule fused together near their attachment 

 to the trunk, but may retain their individuality in the 

 distal segments. Such a specimen is sketched in fig. 

 71. It is a lamb with a supernurn^flfry pair of confluent 

 hind limbs, as shown by dissection, projecting from the 



FIG. 71. A Lamb with coalesced supernumerary pelvic limbs. 

 (After Gurlt.) 



pelvis. In this case the nether opening of the alimentary 

 canal is double also. 



A much more obvious case than this is represented 

 in the chick (fig. 72). For some reason or other 

 supernumerary legs are very common in fowls, ducks, 

 geese, pheasants, and lambs. 



In many cases posterior dichotomy of the axis may 

 be indicated by one limb only, the other undergoing 

 suppression. 



