372 



Harris Hawthorne Wilder 



YIII 



Fig. 2. A related series of Diplopagi, the "Janus-Thoracopagus" series 

 (monophaliens, G. St. Hilaire) : drawn in diagrammatic form from recent 

 cases, as follows : 



I. PROSOPOPAGUS. The "Baldwin Syuote," described in 

 this paper. 

 II. GNATHOPAGUS. Williamson. 1895. 

 III. TRACHELOPAGUS. Fkaseb, 1890. 

 ly. STERNOPAGUS. Sebart, 1896-97. 

 V. THORACOPAGUS. Scott, 1889. 

 VI. XIPHOPAGUS. BoETTCHEB, 1871. 

 VII. OMPHALOPAGUS. The "Siamese Twins," b. 1819; 

 d. 1874. 

 VIII. URACHOPAGUS. Any genuine case of "Duplicate 

 Twins." 

 In the last case (VIII) the imited part does not usually involve the free 

 portion of the umbilical cord, but is confined to the placental portion. If the 

 portion of cord shown be considered to represent the entire extra-embryonal 

 part of the embryo, the diagram correctly expresses the condition. Such 

 twins are thus properly double monsters in which the parts in connnon are 

 extra-embryonal and are cast away at birth. 



