534 Wisconsin Academy of Sciences, Arts, and Letters. 



ends of tlie double vertebral column is a large one, and it de- 

 creases as the degree of bifurcation increases. This applies 

 only to the bifurcation of the vertebral column. The apparent 

 angle made by the divisions does not seem to conform to any 

 rule. 



In the cases of dipropi the rule is the reverse, — the greater 

 the degree of bifurcation, the greater the angle. 



The frontal planes of the two heads do not always coincide, 

 but may meet at an angle. In all the cases of dicephali, this 

 angle was directed downward. Of the three cases of dipropi, 

 the angle was directed upward in one, and in the other two there 

 was no appreciable angle. 



Accompany ing Ahnormalitics. In the cases of dicephali, 

 the necks are likelv to be of different leno-ths, the difference 

 being greater as the necks are longer, though with the data in 

 hand, it cannot be said that tJie difference would be greater 

 in comparison. 



Abnormalities of the shields on the head are not noticeable 

 in the cases of dicephali, except where there is marked defi- 

 ciency, but they are evident in the cases of dipropi, as would 

 be expected. These in-egularities, hovrever, were usually of 

 proportion and of outline, rarely of absence or of redundancy. 



Deficiencies were noted in three cases: VIII, XII, and 

 XIII, enough to lead one to believe that they are frequently 

 correlated with axial bifurcation. Another peculiarity which 

 seems to be correlated in some way is the presence of sharp 

 angles in the vertebral colmmi in Cases YIII and XIII. 



Especial attention has been given in this paper to the point 

 of divergence of the vertebral column. This, however, does 

 not fully express the degree of bifurcation of the color mark- 

 ings and of the internal organs. I think it may be said that 

 when the color markinsfs show a lonaitudinal arransrement, 

 they will be affected caudad to the point of division in the axis. 



Data concerning the internal anatomy of these anomalies 

 are very uncommon, the only instances of adequate descrip- 

 tions being those of Eedi, Dorner, and Borgert. The evi- 

 dence there £:iven certainlv shoAvs that in these cases there was 

 a doubling of internal organs caudad to the vertebral bifurca- 

 tion. 



