of Human Monstrosity. 225 



The structure of the walls of the thorax may be inferred from 

 the description of the external appearance already given. There 

 are twelve pairs of ribs to each foetus. The right sternal series 

 of one foetus, and the left of the other are received into a common 

 sternum : whilst the left series of the first, and right of the 

 second are similarly received into the other sternum. 



The cavity of the thorax is divided into two portions by a 

 membraneous partition proceeding from either vertebral column. 

 In each cavity is a perfect heart in its pericardium, with a pair 

 of lungs : and between the two hearts pass the two tracheae ; and 

 the single oesophagus between them. The hearts are entirely un- 

 connected. And the lungs have this singularity, that of the pair 

 attached to a heart, one is the right lung of one foetus, and the 

 other the left lung of the other foetus. The thorax is closed 

 below by a large diaphragm, with four pillars ; two to the lumbar 

 region of each foetus, with united tendinous centres. In this 

 diaphragm there are double the number of ordinary foramina, 

 one excepted, since there is but one oesophagus. 



The oesophagus opens into a stomach (2J inches long by l£ in 

 width) which rather represents a square pouch than the ordinary 

 curvilinear form of that viscus. One extremity may be called the 

 cardia, because there is a spleen closely attached to it. There 

 is another spleen also, but it is attached to the stomach by a 

 much wider peritoneal fold. From the stomach proceeds the 

 small intestine corresponding to the duodenum ; it is a wide 

 straight intestine doubled upon itself, like the beginning of the 

 coecum in ruminating animals, and lying across the upper part 

 of the common abdominal cavity. To this duodenum there passes 

 the biliary duct from a large liver with a gall bladder belonging 

 to one foetus, as A : but it is not pervious so far as the intestine. 



Vol, IV. Part II. Ff 



