DICHOTOMY. 131 



limbs become dwarfed or suppressed. In some the 

 legs remain separate ; in others they coalesce com- 

 pletely or partially, and in rarer specimens one leg 

 may be suppressed. The relation of the suppressed 

 to the functional pelvis varies greatly. In many 

 specimens it is represented by an irregular plate of 

 bone carrying a limb or limbs wedged in the pubic 

 arch ; in others two fairly-formed pelves may occur on 

 the same plane. The relation borne by the opposed 

 halves of these reduplicated pelves is similar to that 

 which occurs in anterior dichotomy. For instance, we 

 may have a single body with two perfect heads, or 

 the dichotomy of the head is so partial that the jaws 

 in apposition with each other, that is the left one of 

 the right head and the right jaws of the left head, 

 fuse together and form a composite pair of jaws 

 wedged between two functional ones. In cases of 

 partial posterior dichotomy, it has been already stated 

 that the functional legs often belong to distinct pelves, 

 so in many instances of anterior dichotomy the 

 functional jaws belong to two heads. In anterior 

 dichotomy, when it extends into the thoracic region, 

 each individual has a pair of functional arms. In a 

 few cases the median arms, that is the left arm of the 

 right body and the right arm of the left body, fuse 

 together and form a composite median limb. 



Although apparently unconnected with the subject 

 of twin monsters, it is necessary to offer a few remarks 

 on the subject of transposed viscera. Very many cases 

 have now been observed and dissected in which the 

 heart, instead of being inclined to the left sideis 



