Glass 4. RepHKa. 



417 



animal are identical in form (homodont). (For tlie poison teeth of 

 snakes, see p. 423, and Fig. 348) . The tongue, which is attached 

 behind free in front, is very varied in form; in the Crocodilia and 

 Chelonia, it is but slightly movable, with a short tip, and incapable 

 of protrusion ; whilst in the Lacertilia, it has generally a long, often 

 very long, and bifid, tip ; in the Ophidia, too, the tongue is long, 

 narrow, and bifid, and can be stretched far out of the mouth ; here, 

 and in one division of the Lacertilia also, it can be withdrawn into" 

 a sheath on the floor of the mouth. (For the peculiar tongue of 

 the Chameleons, see p. 422). The oesophagus is long, and 

 capable of considerable distension. The stomach of Crocodiles 

 is very muscular, provided on each side with a tendinous disc, to 

 which the muscle cells are attached ; it suggests the gizzard of Birds. 

 The small intestine varies in length, the rectum is short. 



Respiratory organs. The trachea of Reptilia is long, 

 and its wall is strengthened with numerous cartilaginous rings. The 



Fig. 345. — Diagrams of various lungs. A Triton, B Frog or small Lizard, C Tortoise, 

 D Turtle, b bronchus, ft cavity of the lung, a evagination of the lung. Connective tissue 

 clotted. — Orig. 



anterior portion, the larynx, is furnished with special pieces of 

 cartilage, and in some Lacertilia (Geckos, Chameleons), as well as in 

 the Crocodilia, possesses a pair of vocal cords which do not occur in 

 others. The entrance from the mouth is through a longitudinal slit 

 behind the tongue. At the hinder end, the trachea divides into two 



E E 



