Sentence:  Dr. Chapot-Prevost, who successfully operated upon the only other living <WSD>xiphopagus</WSD>, has just published a report of his examination of the new living Chinese twins, Liou-Tang-Sen and Liou-Seng-Sen. 
Meaning of the word marked with <WSD> tags:  Either of a pair of congenitally joined twins ("Siamese twin") united at the xiphoid process.