556 



MANUAL OF ZOOLOGY. 



vertebral ends of the anterior trunk-ribs are bifurcate. There 

 are two sacral vertebrae. The cervical vertebrae have small 

 ribs (hence the difficulty experienced by the animal in turn- 

 ing quickly) ; and there are generally false abdominal ribs 

 produced by the ossification of the tendinous intersections 

 of the recti muscles. There are no clavicles. The sternum 

 is rhomboidal and cartilaginous, sending backwards a pair of 

 "xiphoid" processes. On its face, anteriorly, is a bony "in- 

 terclavicle," while a scapula and coracoid exist on each side. 

 The heart consists offotir completely distinct and separate cavities, 

 two auricles, and two ventricles ; the ventricular septum as in 

 no other Reptiles being complete. The right and left aorta, .how- 

 ever or, in other words, the pulmonary artery and systemic aorta 

 are connected together close to their origin by a small apertiire 

 (foramen Panizzce), so that the two sides of the heart communicate 

 with one another. The aperture of the cloaca is longitudinal, and 

 not transverse as in the Lizards. All the four limbs are present, 

 the anterior ones being pentadactylous, the posterior tetradactylous. 

 All are oinparous. 



The chief points by which the Crocodiles are distinguished 



Fig. 309. A, Head and anterior portion of the body of Crocodilus pondicerianus ; 

 B, Hind-foot of the same. (After Gunther.) 



from their near allies the Lacertilians, are the possession of a 

 partial bony dermal exoskeleton in addition to the ordinary 

 epidermic covering of scales, the lodgment of the teeth in 



