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. Ina 
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 side is 
