574 REPTILES. 



by their sides (pleurodont). Salivary glands occur on the 

 floor of the mouth cavity. The narrow gullet passes 

 gradually into the muscular stomach, which again passes 

 into the coiled small intestine. Near the commencement 

 of the large intestine there is a small caecum. A volumi- 

 nous liver, with a gall bladder embedded in it, and a pancreas 

 are present as usual. 



Embedded in the mesentery below the stomach lies the 

 rounded spleen. A whitish thyroid gland lies on the ventral 

 surface of the trachea a short distance in front of the heart. 



J 



FIG. 197. Heart, and associated vessels, oi Lizard. 

 (After NUHN.) 



A., Right auricle ; jugulars (/.) subclavians (Sc.v.\ and inferior 

 vena cava (I.V.C.) enter it. V., ventricle ; tr., truncus arteriosus ; 

 i, first aortic arch giving off carotids ; 2, second aortic arch ; /.., 

 pulmonary artery ; Sc.a.., subclavian ; Ao., dorsal aorta. A } , left 

 auricle ; pulmonary veins (/.?'.) enter it. In the lizard described, 

 the left jugular is not developed. 



Vascular System. 



The heart is completely enveloped by the pericardium, 

 and is three chambered, consisting of two thin-walled 

 auricles and a muscular ventricle. From the ventral surface 

 of the ventricle arises the conspicuous truncus arteriosus, 



