388 THE ANIMAL KINGDOM. 



latter and in the Lacertilia it is non-glandular like the rest of the tract. 

 The large intestine is short and straight, and it often has a small caecum 

 close to the ileo-colic valve. It opens into a cloaca which has generally a 

 dorsal enlargement, into which the urino-genital ducts open. The Chelonia 

 have a pair of lateral bursae anales appended to the cloaca. And in the 

 same group and the Lacertilia but in no other Reptilia a urinary bladder 

 opens into it ventrally and anteriorly. The liver is bilobed as a rule. It is 

 lengthened out and unilobed in the Ophidia and the Amphisbaenoidea. 

 There is always a gall-bladder which lies removed at some distance from the 

 liver in the two groups just named. The pancreas has several ducts in 

 some Chelonia and the Crocodilia. 



The larynx consists of two arytenoid cartilages borne upon a cricoid 

 ring composed of several united tracheal rings. The trachea is long, and 

 in some Crocodiles and Chelonia forms a bend or loop. It and the two 

 bronchi into which it divides are supported by cartilaginous rings, some- 

 times imperfect, and often united to one another by processes. The lungs 

 are either simply saccular with ridges (primary, secondary, &c.) on the walls, 

 upon which the capillaries are distributed, as in Ophidia and most Lacer- 

 tilia : or the bronchus enters the inner side of the lung, traverses it, 

 retaining cartilaginous semi-rings for a greater or less distance, and giving 

 off eparterial and hyparterial bronchia which divide further as in some of 

 the larger lizards, e. g. Regenia, and in Chelonia and Crocodilia. In some of 

 the serpentiform lizards, e.g. Anguis, the left lung is shorter than the right. 

 This is the case also in the larger Ophidia, but in the majority of that order 

 the left lung is a mere rudiment ; and the posterior part of the right 

 lung is thin and membranous and supplied by blood from the dorsal 

 aorta. In the Chamaeleons and some Geckoes delicate saccular prolonga- 

 tions arise from the inner side and posterior extremity of the lungs and lie 

 among the viscera, foreshadowing the air-sacs of birds. Indeed in the 

 Deinosaurian family Coeluridae the bones of the skeleton are pneumatic to 

 a greater degree than in the majority of birds. The lungs of the Chelonia lie 

 at the back of the thorax and are invested by peritoneum on their ventral 

 surface only. Strong muscular fibres spread into this investment and 

 originate from the ribs. The Crocodilia possess pleural sacs. 



There is a sinus venosus in the heart which opens by a bivalved 

 aperture into the right auricle and receives the vena cava inferior and the 

 two cava superiores, except in the Ophidia where the left cava superior 

 opens separately into the auricle. The septum between the auricles is 

 complete, and the left receives only arterial blood from the lungs. There is 

 a complete ventricular septum in the Crocodilia, and the pulmonary artery 

 and left aorta arise from the right or venous ventricle, while the right aorta 

 is derived from the left or arterial ventricle. The two aortae communicate, 

 however, at their roots by the foramen Panizzae. In other Reptilia there 



