32 



THE PINEAL ORGAN 



Fig. 24. — A Janus-headed Monster, Cephalo-thoracopagus Disymmetros 

 (Duplicitas Posterior). (Redrawn from Schwalbe.) 



The two " secondary " faces Y T +Z l and Z r - Y l are almost identical, and look in 

 a direction which is away from and at right angles to the median dorsoventral 

 planes of the two foetuses. In the disymmetrical type of Cephalo-thoraco- 

 pagus these planes coincide. 



