DUPLICITY. 27 



113. Human thoracopagous twins of small size, with the viscera 



removed to show the union of the thoracic and abdominal 

 parietes from within. The disposition of the ribs is well 

 seen in this preparation. 



114. The heart and lungs of the same. 



The heart is formed of the united hearts of both 

 foetuses ; it is much elongated in the direction of a line 

 joining the two spinal columns. There are two di- 

 stinct ventricles, and a single auricle extending the whole 

 length of the upper part of the ventricles. There is a 

 rudimentary auricular septum. There are two auriculo- 

 ventricular openings, each guarded by a bicuspid valve. 



The cavities of the heart have been laid open. The ventricle on 

 the right-hand side of the preparation has two arterial openings at 

 its base, an aorta and a pulmonary artery, the latter indicated by a 

 blue glass rod. The ventricle on the left-hand side has a single 

 artery or aorta, -which gives off three pulmonary arteries near 

 its origin. This vessel is laid open to show the orifices of the 

 pulmonary vessels. There are four lungs, two on each side of the 

 preparation. Neither set exhibits situs mutatus. 



115. The livers, stomachs, and duodena of the same. The livers 



are united along their whole anterior edges. The sto- 

 machs and spleens are seen one on either side of the liver. 

 The gall-bladder and the ducts of each liver are distinct. 

 The duodena open into a common pouch just below the 

 entrance of the gall-ducts. The intestine was single from 

 the confluence of the duodena to the termination of the 

 jejunum. 



116. The lower portion of the small and the commencement of 



the large intestine of the same. The jejunum terminates 

 in a large pouch, on the extreme left of the preparation, 

 from which two ilea arise. There are two caeca, and each 

 has a distinct vermiform appendix. The large intestine 

 was completely double. 



117. Human female thoracopagous twins about the end of the 



sixth month of gestation. One of the foetuses has syreni- 

 form fusion of the posterior limbs, and there is complete 

 ectopia of all the abdominal viscera. The thoracic cavities 

 have been opened to show the hearts, which are very ab- 

 normal ; one is above the other. The upper heart consists 



