Harris Hawthorne Wilder 417 



E. — DiPLOPAGi Allied to Series A, but with the Separation 

 FROM Below Upward Occurring Earlier than in the Eegular 

 Series. ■ This results in the formation of a median double leg-rudiment 

 in conjunction with a median double arm. 



Ex. — Fenn's fetus, Fig. 4 a of this article. 



F. — Egtopagi Allied to Series A and to E, but with the Sepa- 

 ration FROM Below Upward Still Farther Advanced, giving each 

 body a pair of perfect legs. 



Ex. — Eegnault's ectopage, Fig. 3 of this article. 



Gr. — These are the Craniopagi, of which illustrations enough have 

 been cited to form a series, were it not that they do not show much rela- 

 tion to one another. Thus, in G. St. Hilaire's case, G. I, the two com- 

 ponents are united at their forehead, and in Villeneuve's case, G. II, the 

 union is by the vertices, facing different ways. 



It may be supposed in a general way that such craniopagi as G. I re- 

 sult from an extreme separation from below upwards, as in series B and 

 C, perhaps as a continuation of C. II with more separation from below 

 than from above; and that G. II may be related to it as the extreme of 

 the ischiopagous series is to the rest; but in the absence of intermediate 

 forms all this is a mere conjecture. The fact must be acknowledged that 

 in the case of craniopagi we do not as yet possess sufficient data to form 

 a series suggesting their origin. 



Whether or not separate duplicate twins result from the craniopagous 

 type cannot be certain, but it seems at least possible, and as such G. Ill 

 is presented in the diagram. Such a type of twin, if ever formed, must 

 be very rare, corresponding to the infrequency of conjoined craniopagi. 



H. — Here, as H. I and H. II Eespectively, are Placed PygopagI;, 

 and the Free Duplicate Twins which may Theoretically Eesult 

 FROM them. 



As pointed out above, under series A, the origin of pyopagi cannot be 

 determined, in spite of the frequency of the type, since all diplopagi 

 which may be considered as incomplete pygopagi are thus far lacking. 

 There is a temptation to put them in the missing place in series A 

 (A. VIII), in which case there would be no such free twins as the later- 

 ally related ones figured as A. IX; but they seem to have no more right 

 there than do the thoracopagi. 



At present they are of as uncertain relationship as are the cranio- 

 pagi, and although of frequent occurrence are best left in an isolated 

 position in the diagram. 



In the Above Sketch of the Interrelationships of Diplopagi it 



HAS been often IMPOSSIBLE NOT TO SpEAK AS THOUGH THE VARIOUS 



