Double and Triple Monstrosities 749 



usually easy to differentiate by palpation. Double monstrosities 

 in which the double condition affects the posterior extremity 

 only, if presenting posteriorly, enable the operator to reach for- 

 ward a sufficient distance to properly examine the point of 

 bifurcation and diagnose the double character of the fetus. 



In those cases where the single end of the fetus presents and 

 enters the pelvic inlet, the dystokia is not apparent until the 

 double portion reaches the pelvic inlet and its progress is stopped 

 because of the abnormal size. Then the obstetrist, in making an 



Fig. 127. Tetrachirus Choristocephalus. (Gurlt). 



examination, should be able to pass his hand alongside the single 

 portion of the fetus until he reaches the double portion, the 

 character of which, especially the spinal bifurcation, should be 

 recognized by the sense of touch. 



In the complete double monster, like the thoracopagus and 

 others of similar type, Figs. 126 and 127, the obstetrist finds the 

 two corresponding portions of the body advancing simultaneously, 

 and cannot repel or advance the one without moving the other 

 in a corresponding direction. Moreover, as a general rule he 

 will be able to reach that portion of the two bodies where they 

 are connected, and thus determine the character of the anomaly 

 with which he has to deal. 



In the very rare pigodidymus aversus, Fig. 129, it would be ex- 



