LACERTA 115 



choanae, or internal nostrils. These structures are known as 

 Jacobson's organ, and they probably serve to smell food in 

 the mouth. 



Coelom. — The splanchnocoel is represented by the peri- 

 cardium and perivisceral coelomic cavities. The lungs project 

 backwards into the latter on each side of the stomach, supported 

 by the pulmonary folds of the coelomic epithelium (accessory 

 mesenteries). These folds also connect ventrally with the 

 liver, by the pulmo-hepatic ligaments. The gut is of course 

 suspended from the roof of the coelomic cavity by the dorsal 

 mesentery, and connected with the liver ventrally by the 

 so-called lesser omentum,* also a fold of epithelium. The 

 mesentery ventral to the liver mostly disappears, but persists 

 anteriorly as the falciform ligament. In this manner the 

 coelomic cavity becomes divided up into a number of inter- 

 communicating spaces. On each side of the gut and mesentery, 

 and median to the pulmonary folds and pulmo-hepatic ligaments, 

 is a pulmo-hepatic recess which ends blindly in front, and opens 

 posteriorly into the main cavity. Owing to the kinking of the 

 stomach to the left, the first portion of the intestine (duodenum) 

 recurves to the right, and the right pulmo-hepatic recess forms 

 part of a pocket, the omental cavity. This cavity communicates 

 with the main coelom on the right side by an opening, the upper 

 and front borders of which are formed by the right pulmonary 

 fold and pulmo-hepatic ligament ; the lower and hind borders 

 are formed by the lesser omentum running from the duodenum 

 to the liver, and by the mesentery supporting the duodenum. 

 The opening is the foramen of Winslow, and its relations are 

 important with regard to the inferior vena cava which runs 

 down its upper and anterior border, and the hepatic portal 

 vein, the hepatic artery, and the bile-duct which run along its 

 lower border (see Fig. 125). 



* The lesser omentum is equivalent to the gastro-hepatic ligament and 

 the duodeno-hepatic ligament : portions of mesentery connecting the liver 

 with the stomach and the duodenum respectively. 



