344 



CLASS REPTILIA. 



bronchi are short and open into the lungs, which are sacs witli 

 honeycombed walls. In the chameleons and some geckos 

 the posterior part of the lungs is produced into narrow 

 diverticula which lie among the viscera and foreshadow the 

 air-sacs of birds. In the snake-like forms the lungs are often of 

 unequal size. 



The brain has a small cerebellum. Almost all lizards appear 



Fig. 189. — Longitudinal section tlirough the connective tiusue capsule and the parietal organ 

 of Hatteria punctata (after Spencer from Wiedersheim). g bloodvessels ; h cavity of parietal 

 organ ; k connective tissue capsule ; I lens-like thickening of the dorsal wall ; r retina- like 

 part of the parietal organ ; m molecular layer ; st cord connecting the organ to the pineal 

 body ; x cells in st. 



to possess a parietal organ * (Fig. 178) lying in the parietal 

 (pineal) foramen or just below it, and often in close relation 

 with the skin. This organ is a vesicle the walls of which may 



* H. W. de Graaf, Bijdrage tot de hen. van d. Bouw en de Ontwichkeling 

 der Evivhyse hij Amphibien en Reptilier, Leyden 1886. Spencer, Q.J. M.S. 

 27, 18S6. B6raneek, Jen. Zeitschr., 18S1, 21. Leydig, Biol. Centralbl., 8, 

 1889, p. 707 and 10, 1890 p. 278 ; and Abh. Senckenb. Nat. Qea., 16, 1890, 

 p. 441-551. 



