MoXSTJiOS/TIES. 



407 



Those monstrosities which are characterised by the al)iioriiial situa- 

 tion and form of dilTerent parts — and wliich are inckided in Class 

 first, Order six, of Clurlt — are not exceedingly rare, and in some 

 instances are probably due to muscular contraction, or malposition 

 for some time in the uterus (Fif^. 114). 



Saint-Hilaire divides the double monstrosities into two orders : Aiitu- 

 sitaric and Pdrasilic ; the former beinj^ constituted by individuals more 

 or less intimately united and somewhat ecjually developed, each con- 

 curring to the mutual existence : while the second is made up of those 

 monstrosities which, though united, have one being more or less com- 

 plete — being reduced in fact to a linil), jaw, or other fragment of a body 

 implanted or subsisting on an individual which is fully developed. 

 These are included in Gurlt's second Class. 



In the autositaric order we have the Eusomphalian and Monomphalian 

 monstrosities : these have the common character of two heads and four 



Fig. 114. 

 CamylorrhnrrhU contortn. 



pairs of limbs ; the first have, however, a distinct umbilical cord to 

 each of the united fcrtuses ; while in the other — the Monomphalian — 

 there is only a single umbilical cord and umbilicus. 



The Eusoniphalian monstrosity consists, then, of two pretty equally 

 developed fcrtuses, each with its own umbilical cord, the two being 

 usually joined together by some soft part at any region of the body ; 

 so that they may be separated by a surgical operation without the 

 existence of either beinu' compromised. This is included in the third 

 Order of Gurlt's second Class. 



With the Monomphalian monstrosity, on the contrary, there being 

 only one umbilicus and one cord, the foetuses are joined at the ventral 

 surface, and have usually several organs in common — notably the liver, 

 to which the umbilical vein passes (Fig. 115). 



The Si/nccphalian monstrosities have two bodies either completely 

 separated, or only divided above the umbilicus, and surmounted by a 



